So basically I want to join line that starts with “\n” with previous line and I don’t want to delete this “\n” symbol. Any ideas how to do this?

Using a regular expression in the “Replace” function we have:
Find What:(?-s)\R^(\\n.+)
Replace With:\1
So search mode must be regular expression. Click on the “Replace All” button to change the entire file.

You will see the \\ in the expression because the \ is regarded as a special character, so the additional \ escapes it, or reverts it to a normal character.

Terry

PS since you didn’t show the example inside of a black box (read the “read me before posting”) it’s possible this might not work. I suspect you may have leading spaces on some lines.