Hello, and in this case, if you have all the clips in MixPad, you can use the Frequency analysis of the whole project, and once you see which are the frequencies that overlap, use the cleaning tools to remove the frequencies, for example, use the option to grab a noise from a selected area, and then use the Special subtraction based on noise sample.
If the audio file is already mixed into a stereo or mono file, there is no way to edit it to remove specific frequencies as specific, the clean up tools will be applied to the whole track which may affect other sounds within the same frequencies.
For further support you may want to contact the NCH Software support team through this link Software Technical Support