Hey gentle man
Hi
you have many simple way: first way: use notch filter with narrow Q factor. second way : feed back in frequency of noise. or ..... etc!
Best Regards
Goldsmith
You'll have to be more specific about your noise and signal characteristics.
Anything that removes noise from a signal is pretty much a filter by definition. So either you'll need one, or you'll have to prevent the "noise" from coupling to the signal in the first place.