You can't set a single bit to a 0 and a 1 simultaneously. What exactly do you want to do?
You can set a bit to zero by ANDing all other bits with 1. To reset bit 4 of an 8-bit int X for instance you would do X &= 11101111b (using the C bitwise and-assign operator; translate according to your CPU).
You can set a bit to 1 by ORing the bit with 1. To set the same bit as above you would do X |= 00010000b (using the C bitwise or-assign operator).