Uninstalling R and R Studio from the mac
From https://cran.r-project.org/bin/macosx/RMacOSX-FAQ.html:

1.3 How can R for Mac OS X be obtained and installed?
[...]
Further details, including uninstallation and building R from the sources, are in the ‘R Installation and Administration Manual’.

Said manual is at https://cran.r-project.org/doc/manuals/r-release/R-admin.html.