guideline to remove previous julia installations completely

[mohamed-180]

Based on the discussion on Julia discourse

Would we add some guideline to remove previous julia installations completely before use juliaup installations and noted in installation page Or make it the in setup operations .

Originally posted by @mohamed-180 in #773 (comment)

[AnjoMan]

this is maybe a bit tangential but i've run into this issue with juliaup config files: juliaup won't run in non-interactive mode if there is an existing config, but i don't know where the config is. an easy solution would be to print out the location of the conflicting file, but maybe a more useful solution would be to add an arg to ignore / overwrite it