Q:

Is WesternDigital Dashboard needed to trim a SSD?

Based on this question Why do we need Intel SSD Toolbox for TRIM? it seems that there is no need to use vendor's application to trim.
But although I'm sure Windows 10 trim is not disabled but in WD Dashboard there is a checkbox "enable trim" which is not checked so now I'm not sure what is the real status of trim.
My way to check trim is from online:
fsutil behavior query DisableDeleteNotify

the result is "0(disabled)", which means trim is enabled. I'm not sure whether this is enough and why there isn't an UI to show information as important as this.
Another question is will windows do trim when I delete a whole partition?

A:

The checkbox in the WD software may well be to have that software manually initiate a TRIM on a regular basis.
If TRIM is indeed enabled in Windows then it will be run on a schedule as the Disk Optimisation tool (the same tool that occasionally defragments HDDs) runs. Instead of defragmentation the tool will simply TRIM SSDs.
If you go to your disk properties and then Disk Optimisation you will see what type of disk it is and what it will do:

You'll notice that it shows "optimise" rather than "defragment" for SSDs.
When you click "optimise" for a drive it will say "25% trimmed" and so on instead of "xx% defragmented". The process of TRIMming should not take particularly long.
The image came from NextOfWindows, that page also describes how to get to that tool.
Your command shows that TRIM should already be enabled.

