Audacity should work, it is cross-platform and has become quite fully featured. But I don’t know what sort of de-noising it offers.
My go-to has usually been SparkXL, which is now old and unsupported. But for scratches and pops I have usually done manual cleanup, which can often be done with any two-track editor and some patience. It’s easy if the noises are mainly in the silent bits. Otherwise it requires some guesswork to restore the affected audio. Sometimes you can isolate a bit of hiss, pop, or scratch in a silent part, and use convolution to subtract that same sound from the musical parts, with varying degrees of success.
