If I do:
env
It will print out all the environment variables. Is there a way to delete all variables without looping through them individually in Bash?
Yes, but be careful what you wish for:
$ unset $(env | awk -F= '{print $1}') && env
bash: env: No such file or directory
The 2nd call to env(1) fails because PATH has been deleted.
An alternative might be exec -c, to execute some command from a subshell with no environment. But a better route, if you're worried about too much stuff in the environment, is to look back and see where that excess stuff came from, and clear it up there.