That is normally done in Windows, CP - Display - Settings - Advanced - Adapter. Your adapter software integrates itself in Windows. Example . . . Radeon 64 DDR the gives you choices of:
Adapter Default
Optimal
60 MHz
70 Mhz
75 MHz
85 MHz
100 Mhz
The fastest isn't always the most stable. Anything over 75 is flicker free to the normal human eye. A lot depends on your monitor's capability. You need to read its manual to find out what it is capable of. Setting a refresh rate that the monitor is no capable of can be harmful to its longevity. It also relates to the selected resolution and color depth.
There are of course, separate programs that do that, but until you really understand what you are trying to do and why, I would study the issue further.