There is no formal appeals process, and "abuse" is a concept that's not as clear cut as some people think it is. For now, admins have a fairly free rein; unless they violate the Terms of Use no action is taken. You can always inform staff of your concerns with the contact form.
Also, most people who complain about admins here tend to be in the wrong... so be careful throwing out accusations.
FANDOM staff rarely intervene unless an admin violates the Terms of Use.
@Marvel Stadium. Will you please leave me alone? How many accounts will you make just to roast me? Gosh...
If you suspect the user of ban evasion and sockpuppeting, you should report them or things won't get better.