Notepad++ delete until colon for every line with replace all

Use the "Extended" setting in the Replace window (not "Regular expression": I'm sure there's a way to do it with Regular expression, but using "Extended" works fine).
Enter ".pPrev.\r\n" in the "Find what" field, and leave the "Replace what" field blank. This will include the \r\n characters in the match and delete the whole line.

Depending on the scope of replacement, you have two approaches:

1. Install plug-in manager for Notepad++ and Compare plug-in, it's great for comparing contents of two files. If you just want to replace some text (one or more words) with other text, you can do it manually by using search and replace in Notepad++. That's suitable solution if you have small number of such texts or if text to be replaced is short.

2. If number of such replacements is high, and if you need to do such replacements often, then you need something like Unix diff and patch, and there are lot of such tools for free for Windows. Usage is simple - output of diff tool is a patch file which you can apply (with patch tool) to second file to get both files the same. Simpler is to copy file, but if you do not want whole files to be identical, but only some lines, edit patch file (it's plain text file) and just remove what you don't need.