You cannot withdraw cryptocurrencies directly to a bank account if you think in that direction - you have to sell them and then make a transaction to your bank account. If you don't want to sell everything, you can sell only a part and leave the rest in the wallet - or move to another wallet of your choice.
I would suggest using Coinbase for this unless of course, the BTC is already sitting in an exchange rather than a non-custodial wallet? But I would doubt that.
Since the OP has inherited accounts, one of which is on Coinbase, I don't know what the legal situation is in case he makes a direct sale from an account that is not in his name - maybe it would be better to make accounts in his name and transfer crypto there before start trading.
At the moment in my possession i have Bittrex and Coinbase secret codes. I also have to log in details to get into these websites but the main issue is the Goggle Authenticator. I just cant get in. Iideally i would like to transfer the 2fa details to me and my mobile phone.