If your EOS is used for voting and being processed as a collateral, then your EOS can be redeemed thereafter. However, the corresponding ballot is nullified in the meanwhile.
How to do it?
1. Enter the "EOS Voting" page and click on the button at the upper right corner to the "My vote" interface.
2. Click the "Redeem" button to cancel your previous voting. Then proofread the information popped up and enter the password.