We are going to use NotePad++ replace functionality (CTRL+H) to remove all multi-line comments that are enclosed in a pair of /* and */.
While in the source file you want to edit, open up the ‘Replace’ window either from the ‘Search’ menu or by using CTRL+H.
Set ‘Search Mode’ to ‘Regular expression’ and tick the ‘. matches newline’.
In the ‘Find what:’ input type
/\*(.*?)\*/\n and leave the ‘Replace with:’ input empty.
To make the change on all comments just hit ‘Replace All’.