The only way to terminate a license is to go
Top > Service Director > License Manager > Licenses, click on a license and press Terminate.
Is it possible to terminate more than one license at a time?
That is possible since OBAS 4.5.6 release by selecting required licenses and pressing the Terminate button that appeared above the licenses list.
To resolve the issue, please upgrade to 4.5.6 as described in How to upgrade OBAS system to the latest available version.