Hello Hac

I'm sorry but I don't understand what you want to hide, the first available time slot, or the start time?

If it's the former, you can only modify your employee's working hours so it starts later, and that first time slot is skipped.

Hello Hac

You mean the back-end calendar?

The back-end calendar is set to show two hours before employee's working hours start.

If your default time slot step is set to be half an hour, it should look like this:

But if you lower that step, so it's (for example) 15 minutes, it will be split into 15-minute periods, like this:

This is something that can't be changed yet, unfortunately, and the only thing here would be to increase the time slot step. Of course, if you need a shorter step, there's nothing we can do about the issue I'm afraid.