Is it OK to edit my undergraduate thesis results? I'm current an undergraduate student working on a research project for my thesis.

In my project, I obtained quite a large number of inconsistent or strange result for my lab analysis of my samples and I just couldn't get a reliable or sound result for my analysis. I have been struggling in repeating the experiments for a prolonged time and done a lot of attempts, yet I still have not got a good result for it.

While my viva session and thesis submission date is approaching nearer, I am really stressed and have thought about modifying my lab results so that it is more presentable for my thesis since time is running out. 

However, I really am not sure whether that is it ok for me to do so. I got a guilty feeling that I am doing something that is against my morality for submitting results that are not 100% originated  from my own work. On the other hand, if I report my original results that didn't look appealing for my supervisor, I'm also afraid that she would require me to redo my whole experiment and delay my graduation date.

I really hope I can get an advice from a reliable researcher or student about my case.
I am really stressed up and conceived the notation of modifying my lab results so that it is more presentable for my thesis since time is running out.


No, no, no

Never do this - it is highly unethical. If your deceit is discovered, you are likely to lose your degree, and may possibly face other consequences. (For example, if you have a job based on that degree, you may lose the job when the degree is revoked.)

It is always disappointing when a project doesn't work out the way you hope it will, but there is always that risk when you set out to do something that isn't completely straightforward.  See, for example, this related question: What to do when research leads to poor results? 

Even experiments that are "known" to work (in the sense that someone claims to have previously achieved "good results" with that experiment) can't always be repeated reliably. See Estimating the reproducibility of psychological science, in which the authors attempt to repeat 100 published psychology experiments, and "replicated the original result" in fewer than half of them.

The correct response is to 
write your thesis giving all the details of your work as it happened: the background, the experiment design, and the results. This serves to document your efforts, and may prove to be useful to other people who might try the same experiment in the future. You may also explain why you think the experiment may not have yielded the results you expect, and possibly propose a new experiment (if you have any ideas for improving your work).

Note that even when scientific findings do not match our expectations, the study is still considered a success (of sorts) if we can learn something from it. Even if what we learn is "this experiment does not yield consistent results in many cases." In contrast, false results might look nice, but are worse than worthless.

A lack of "good results" does not necessarily doom your thesis. To quote another answer:


  My PhD thesis was trying to demonstrate the nature of the relationship between stress and psoriasis symptoms (many people say "stress worsens psoriasis" - it's taken as a given truth, but it's never been empirically demonstrated). I was trying to answer things like what kind of stress, how long does it take, does it differ between people? I never found any evidence that stress did worsen psoriasis. Nor that psoriasis worsened stress (or any other psychological symptom).
  
  A PhD is an educational process. One should demonstrate that one has learned. The most important thing about a PhD is showing what you know, what you have learned, and what you understand. If anyone gets to the end of a PhD and says "Well, those results were all positive, just as I expected", they've learned little. At the end of your PhD (or any research project) you should want to start again, and this time do it properly.


The excerpt above is about a PhD, but applies at all levels of study.


  If I report my original results that didn't look appealing for my supervisor, I'm also afraid and doubt that she would require me to redo my whole experiment and delay my graduation date.


You should talk to your supervisor now - don't surprise her the week before your submission date and tell her that the experiment failed! Talk to your supervisor and ask for her advice on how to proceed with your experiment. Presumably she has more experience than you in this area and may be able to suggest a solution you haven't thought of. (And she probably does not want to delay your graduation any more than you do...)