No. If you delete migrations that have completed a Pre-Stage pass or a Full pass, the associated licenses will also be deleted. This cannot be undone and will require that you recreate the migrations and use additional licenses to run them again.
Note: The User Migration Bundle license is an exception to the above rule, as it is applied directly to the user being migrated and is independent of MigrationWiz. Therefore if the project is deleted, the license remains assigned to the user and is not lost. Before deleting any projects due to issues, contact BitTitan Support for help.