As you've not uploaded a sample, I can't say for sure, but the first step should be trying to understand where exactly the noise is. To do this, you can use spectrogram view that shows your audio file as a sort of heatmap.
Below is a sample audio file to which I've added a noise tone; this is just to illustrate, your real noise will look a lot different and probably a lot fuzzier.
At the side of the screen in spectrogram view is a scale that shows the frequencies. Once you've identified the noise signal, check where it falls on the frequency scale, e.g. the noise in this example lies between 300Hz and 500 Hz:
Then you can take steps to fix this. The trick is to reduce the volume of the noise selectively without affecting too much of the rest of the audio. The easiest, fastest and most brute-force method is to use an EQ curve effect. This can be found in the "Effect > EQ and Filters > Filter Curve EQ" menu item. Make sure your track is selected, then open up this effect and you'll see a window like this:
The bottom of the graph represents frequencies. The left axis represents gain (think of it as volume). The green line represents the gain/volume of the audio as it is currently. Clicking on that line adds control points that you can drag up or down. For this I like to create 2 points on the line as the limits to what frequencies to affect (here I added them at 300 Hz and 500Hz), then add two more points that I drag down to coincide with roughly where the noise is on the graph. The end result looks something like a triangle, as shown below:
You can refine this further by moving the points around a bit while listening to the audio on loop. This should result in slightly muddy or tinny audio, but if you do it right it will reduce the noise without sounding heavily distorted. If you upload a sample, I'm sure someone can point you at a much better method.
