Unable to clear safari history

Yes- the clear button is greyed out. I just spoke to Apple support and helped resolve the issue. The reason the clear history button is grayed out is due to the fact that I have enabled Screen Time for my kids. Disabling screen time will then allow your kids to clear history. I think it’s a safety measure to allow parents to view sites their children go to and to track activity.

Is clear button grayed out?

i Have checked and my children’s phone do not have any restrictions except for when downtime is on. Otherwise all setting are unrestricted

Have you checked Settings/Screen Time for any restrictions?