I assume that you are talking about CY8CKIT-059.
And if you are not connecting the board to external peripherals
which sends or receives current from/to the board,
I think that you can just disconnect the board from the PC.
At least I've been doing so for a few years now.
P.S. As you wrote when you are done it is OK,
but please avoid disconnecting while PSoC Creator or PSoC Programmer is writing a program/data to the board.