You cannot disable resampling - everything is automatically resampled to the project sample rate. So if you open a 48Khz file in a 44.1 Khz empty project your file is resampled when you export.
Seems like the obvious solution is to not open a file of sample rate A in a project of sample rate B. Just make sure they match; this is very easy to do. (While an easy answer, I suspect your IF is simply one example of perhaps many).
Not sure why one would want to open a file of Sample Rate A in a project of Sample Rate B, unless one intends to mix two sources of different sample rates - in which case the mixed down file will always have a single sample rate, anyway: A, B, or C (i.e. different from either of the source files). How else would an app mix down two sources of differing sample rate except via sample rate conversion?
Maybe I'm misunderstanding the issue. Hmmm.
To the best of my recollection (admittedly vague at this point, since I've not used some of them in a long time), every audio editor I've used (Audacity, CEP/Audition, Samplitude SE, can't recall with great confidence in Wavelab or Reaper) requires the audio file sample rate to match the project sample rate.