How to revert jenkins Safe restart?
I assume you talk about jenkins cli?
There is no command to abort the safeRestart.
Use quiteDown, cancelQuietDown instead and safeRestart only if needed.

safeRestart: Puts Jenkins into the
quiet mode, wait for existing builds to be completed, and then restart
Jenkins
quietDown: Put Jenkins in a Quiet mode, in preparation for a restart. In that mode Jenkins don’t start any build
cancelQuietDown: Cancel the effect of the “quiet-down” command