While coinbase accepts ethereum, funds internal to their platform are not moved from wallet to wallet, but are kept track of in a database. Sending ERC-20 token (none of which they support right now) will simply result in their loss
I know this becuase my silly firend asked me to send bubbletone tokens to his coinbase account. They are gone.
get a ledger. Use MyEtherWallet. Best way
To be honest, I still wonder who would send an ERC20 token like UMT to coinbase, I mean it doesn't cost a dime to use Metamask, IMToken wallet or even MyEtherWallet. All these are readily accessible.