Please do this the other way around: complete your tax return in TurboTax first before calling your HSA custodian. At least do enough of your tax return to see what TurboTax tells you what the amount of the excess is.
The reason is that you want to know the exact amount of the excess contribution so that when you call the HSA custodian (yes, before April 15th) you will have the correct number. Withdrawing random amounts of money can expose you to penalties.
When you call the custodian, be sure to tell them that you want to make a request for the "withdrawal of excess contributions" (use this exact phrase, so they get the paperwork right).
What is important is that you get the request in to the HSA custodian by April 15th, not that you actually get the money back by then.
Note that when TurboTax gave you the message that there were excess contributions, it added the excess to Other Income on line 21 on Schedule 1 so you don't have to do anything about that. As for the earnings on the excess, you will receive a 1099-SA for this in early 2020 so you will report it on your 2019 tax return.
Once you do that, you can finish your return and file it, telling TurboTax that you will withdraw the excess before April 15th. Like I said, what matters is when you request it, not when the HSA custodian gets around to it. To be safe, though, make a record of when you do it (or take a screenshot if you can do it online) and stick it in your file with your tax records.
If anyone ever asks you about this (not very likely), then this is your response: "I made the request in time".
If, in fact, you are confused about something else, please let me know.