Just signed up with QB Online Simple Start (from QB Desktop 2017). Can I pay employee manually? (Not using payroll service) There's only have 1 employee.

Welcome to the newer, even more greedy Intuit. Quickbooks online does not have a manual payroll option. Here is the pricing: https://quickbooks.intuit.com/payroll/pricing/

Yes, you read that right, for that ONE employee, you have to pay $75 + $5 = $80 a month or $960 a year...and that's per company so if you have another business that's another $960. Right now they have a "first 3 months 1/2 off" special but don't fall for that.

I suppose, and maybe someone else can chime in, you could just write him a check and then do manual journal entries or something but that's just asking for an error. 

Our business only has 3 employees and we had been paying the $700ish annual payroll subscription which forced us to upgrade our Quickbooks Desktop Pro every 3 years.  We weren't happy but held our nose and paid it.  This year though we found out that we'd either have to go to Quickbooks Online which is a non-starter for us, or pay $549 a year for Quickbooks Desktop Pro 2023.... but Intuit isn't getting that money from us. 

We're going back to manual payroll and holding on to our desktop program for as long as we can. If you are not in too deep on QB Online yet, you might consider cancelling your subscription (ask for refund) and sticking with your old software.  Maybe if enough people do this, they get the message that people are not happy.