Hello, here is the easiest way in my opinion to delegate Steem Power to other Steemit user
https://helloacm.com/tools/steemit/sp-delegate-form/
You need to just simply write your login, to who you delegate login and how much SP you want to delegate.
If you need to undelegate Steem Power you can use this tool too and just than you need to write zero in amount.
If you have any question let me know! In my opinion is much easier than count vest.