You an send them a secured message to just lower your limit. I do this now by around 3k from one of my cards before applying for a new card. Has helped a ton with getting auto approvals. I got tired of calling recon after the fact to get things moved around.

You dont need to cancel cards, just secure message that you want to lower the limit of card ending in XXXX by whatever amount. Typically 3-5k is enough wiggle room for auto approval.