In Bitcoin, we don't spend funds by looking at the balance on addresses. Instead, we spend inputs and create new ones. Let me show you an example: https://blockchair.com/bitcoin/transaction/c21523ed3745959ce1389f571ec1c46181eb09c10d85301923bf875cfc0fd1b9. The transaction has 3 inputs, by spending them, I've effectively created a single input for the next address. If I were to replace it with any address that I own, then I would've effectively consolidated it by spending 3 inputs and creating a single one.

If you were to spend 15 inputs in a single transaction to your own address, you'll create a single transaction output for it to be used in the next transaction. The other 10 inputs can then be spent in another transaction to create another inputs. Afterwards, I'll just use the two inputs that I've created through the consolidation into the transaction that I originally wanted to make, but was unable to do so due to the restrictions on the number of inputs.

So, create a transaction that sends back to your own address; Go to View>Tools>Show Coins, then select any inputs, as long as there isn't 20. Go to your Send tab, input an address from your own wallet and press Max. Afterwards, do it as you would for a normal transaction. Upon loading it into ColdCard, you should expect to see a message saying that you're sending it to your own wallet.