Remove exact line from file if present, leave the rest of lines; error-handling - how to go about it

I am not exactly sure how text processing should be done in a good way, so let me ask. I have this file: ~/.config/mpv/input.conf containing possibly other options as well as v disable. If I want to remove that line from the file, I suppose I could do:

-sh
grep -v -q -F 'v disable' input.conf; echo $?
1

Where - if the file contains nothing else like now, it would return 1 (man page says 1 - "No lines were selected."), which troubles me as I cannot run a simple if-statement. So I would have to store $? after the command and then check if it is greater than 1 for error. Also, it is unclear to me, if replacing the file in-place is a good idea:

-sh
grep ... input.conf > input.conf

--- If there is some other way, let me know. Also if portions of my suggestions are correct, please let me know. Thanks, and cheers. --- EDIT1: Desired behavior is to toggle between the state where there is this line (done with simple >> addition after a check if it is there, and is not (remove it, thus this question). EDIT2: The accepted solution must be POSIX-compliant. No _bashisms_ or non-POSIX tools. You can, however, include non-POSIX solutions which might be useful for other people. In any case, thanks.