You can merge question pools to move all of the questions from the source pool to another question pool. You must merge question pools if you want to delete them but keep their questions.

When you merge a question pool, you select a source question pool, topic pool or sub-topic pool, and a target question, topic or sub-topic pool. Questions from the source pool and all of its sub-pools are moved to the target pool. You can then re-assign the questions in the target pool to other question, topic or sub-topic pools in the Administration tab of the Question Editor, or by exporting the questions to a CSV file, updating their pool assignments and re-importing them via the Question Data Loader. 

Administrators with unrestricted access to the Exam Utilities feature in System Roles (Manage Features > Exam Manager Features) can merge question pools.

To merge a question pool

1. Go to Manage Center > Learning > Question Pools Manager. The Question Pools Manager page opens.
2. Select Merge Pools.
3. Select the pool you want to merge from the source drop-down lists.
4. Select the pool you want to move the source level questions into from the target drop-down lists.
5. Click Submit. The page refreshes with a list of the questions that were moved.