I want to replace a dual switch/receptacle in the middle of a GFI series - with just a switch (the dual switch/receptacle is not available in the designer color I want). Can I do this and maintain the GFI protection of the downstream receptacles?

Not sure if I am understanding you correctly. If your in the middle of a GFI circuit, this means the GFI protection device is at the beginning of the circuit, and the circuit will remain GFI protected. Would you agree?

The receptacle is in the middle of a circuit as part of a switch/recepticle combination. When I install the new switch and remove the switch/recepticle combination, what do I do with the wires that went to the receptacle - just cap them off?

Thanks

OK got it. Yes, any wire not needed for the switch, such as the white Neutral for the outlet can be capped with a wirenut. The black hot that feeds the outlet may be the same hot that feeds the switch, so this wire will be needed.

Be sure to know which side of the switch/receptacle combo is hot, and which wire is the switched leg. If you lose track of this you will have problems.