If so then you probably have not caused any damage.

That said, it might be good practice not to power-down/turn-off the computer via the surge protector but instead power down (or shut down) the OS as normal, (eg in Windows this would normally be via Start > Shutdown), then turn off the tower's supply by turning off the PSU's switch.

No need to turn off the surge protector.

That would be my procedure

Mark