Yes. If you delegate 0 SP to a user, it will remove the delegation. After the cool-down period, it will return to your account and you can reuse again.
Here is a link with instructions on how to do delegations:
https://steemit.com/delegation/@timcliff/tutorial-how-to-delegate-sp-to-another-user-using-the-steemconnect-tool-from-busy-org
Awesome! Thx for the 411 :)