I like very much a performace. I would like to know how to remove the sound of the push button and the applauses from the audio I downloaded. Is it possible? Thanks in advance.
That’s not possible. 
In general, you can’t un-mix audio. Of course you can isolate the left & right and there are “tricks” for isolating or removing “centered” vocals.
…There is a tool called spleeter that’s supposed to un-mix to some extent but I haven’t tried it.
How long is the recording, and how many months are you willing to spend “fixing” it?
It “may” be possible to remove the button clicks one at a time by using a combination of these tools:
https://manual.audacityteam.org/man/spectral_edit_multi_tool.html
https://manual.audacityteam.org/man/spectral_delete.html
https://manual.audacityteam.org/man/repair.html
https://manual.audacityteam.org/man/copy_and_paste_a_section_of_audio.html
but it will be horrendously time consuming.
Applause between songs can be easily edited out, or reduced in level using the “Envelope Tool” (See: Envelope Tool - Audacity Manual)
For more automated fixing, the “Pop Mute” plug-in “may” help to reduce the clicks / applause, but whether or not this is useful depends on the actual audio. See: Missing features - Audacity Support
Installation instructions for Nyquist plug-ins are here: Missing features - Audacity Support
I’ve tried it. It is a very “technical” tool.
In some cases it can do a very impressive job, but in other cases it is completely ineffective - it depends on the audio.
Spleeter is available here: GitHub - deezer/spleeter: Deezer source separation library including pretrained models.
(Please note that Spleeter is not our product and we are not able to offer any support for this app).