My check engine light is on on my 1998 GMC 1500 truck. Could someone please tell me where the reset button is.

There is NO re-set button. You need to scan the computer and see what codes are stored, repair the problem, and clear the codes.

There is no reset button. You cannot remove the battery cables to reset it either. The only way to clear the code is to fix the problem and let the computer figure that out or clear the code with a scanner. Of course just clearing a code does not mean it has been fixed as the PCM will again test that circuit and if it finds it in error, it will turn the light on again.

there is no reset button. The vehicle needs to be scanned to find what trouble codes are present, then repair the defect, then clear the codes. to simply clear them would not help, since the light will come back on once the pcm detects the fault again.

taking the battery cable off will not help obd2 which your truck has you need a scanner to clear code and while your at it have code read more than 1 thing is programed into computer to set light autozone and advance do this for nothing

Sounds cool

take battery cables off for a minute or two then put them back on or check your gas cap