Remove blank lines: tabs, spaces, (\s) using regex

[r0n]

Sorry for this very simple question.
But I have a lot of trouble tackling this seemingly very simple request:

A string

Code:

Copy      Help

abc


def

The line(s) between between abc and def must be removed IF it contains:
- one or more spaces / one or more ALT+255 chars (nbsp)
- one or more tabs
- one or more ENTERS / SHIFT+ENTERS

It can be a combination of the above

I have tried many regexes containing:

• /s
  
• /t
  
• /W
  
• [] (topic: Problem Stripping line returns)
  
• beginning expression: ^ and end expression: $
  
• /r/n
  
• /b

But it constantly creates 1 line (see below) OR it does nothing and thus keeping the original result

Code:

Copy      Help

abcdef

in stead of the desired result:

Code:

Copy      Help

abc
def

How I build the regex:

- I always start the regex by placing the cursor at the beginning by using: ^

Then I follow with

- zero or more spaces: \s*
- zero or more tabs: \t*
- followed at the end by a carriage return and newline: \r\n

I combined that with the previous mentioned: $ ,\w , [] but I end up with all on one line OR no changes at all.
This is really weird for me, because I have solved complexer regexes much easier in QM.
But this simple thing I cannot solve.
(also tried regexes from stackoverflow.com, but also constantly no result or everything on one line)