"때려쳐" has nothing do with "slap"or "hit".
It's a slang and informal expression between close friends so you should be careful in saying "때려쳐" or 때려치우다."
The basic form of "때려쳐" is "때려치우다" which means abruptly or unexpectedly abandoning something that someone is doing. If you are told this expression, the speaker might be really in bad mood for some reason.
For example, when a boss hears a lot of complaint from their colleagues, he/she could say "If you guys can't stand any longer, quit your job" with anger. At this sentence,"quit your job" could be translated into "다 때려쳐".
When we give up something with a bad reason, we say "~을 때려치우다."
Therefore, "때려쳐" is the imperative sentence of "때려치우다"
학교를 때려치우다 give up going to school
사업을 때려치우다 give up running a business