Q:

Deleting a row which is substring of the subsequent row

In Libre office calc , I have a criteria where in I need to delete a row in case it is substring of the previous row .
i.e
If the input is

ABC
ABCDE
XYZ
XYZRE

and I apply the regex , the output must be

ABCDE
XYZRE

A:

You need to capture a line, then a linebreak and then use a backreference to the captured group value to make sure the next line starts with the whole line before it. 
Use
 ^(.+)[\r\n]+\1

Replace with 
 $1

Some editors require \1 instead of $1.

