Wikipedia:Admin functions that should be performed only by admins who are adults
There is no requirement that administrators on the English Wikipedia be of any particular age. Historically, there have been administrators (and at least one bureaucrat) who had not yet reached legal age. In fact, because there is no age verification process for administrators (as there is for certain other userrights), the fact that a given administrator is a minor may not even be known, unless he or she has disclosed the fact voluntarily.
Younger administrators have the same administrator access, rights, powers, and tools as all other administrators, and are subject to the same standards of administrator behaviour.
However, there are certain specific types of issues that it is usually best for younger administrators to leave to their older colleagues. Some of these situations are discussed below.
Dealing with threats
Wikipedia has policies that prohibit editors from making threats. This includes threats to cause physical harm, to take action against an editor off-wiki, or to bring a lawsuit against an editor or against the Wikimedia Foundation. Younger administrators usually should not be the ones to enforce these policies (e.g. by blocking for a legal threat) themselves, but should bring them to the attention of others.
Dealing with alleged paedophiles or paedophile activists
Enforcement of policy and practice concerning pro-paedophilia advocacy or editing by alleged paedophiles should not be handled by administrators who are minors. Anyone of any age with a concern about an editor's conduct in this area should not raise it on-wiki but should privately advise the Arbitration Committee by e-mail.
Dealing with articles relating to pornography
Because Wikipedia is an all-subject encyclopedia and is not censored, the contents of the encyclopedia include material that may be considered inappropriate for minors. Administrator actions relating to these types of articles are best performed by non-minors.
If in doubt
All administrators are unpaid volunteers and are free not to involve themselves with any issue or to withdraw from dealing with a given issue at any time. This can be done either by referring the requester to the relevant noticeboard; by posting a request at WP:ANI for an uninvolved administrator to take over; or by raising the situation directly with another administrator when appropriate. There is no need for a younger administrator, or any other administrator, to deal personally with any situation that makes the administrator uncomfortable.
A younger administrator who is uncomfortable with a situation, particularly if there is concern that it may have off-wiki ramifications, should also discuss it with his or her parent or guardian.
Editors, including administrators, must not share their Wikipedia passwords with others. Administrators are entrusted with access to information that is not publicly available. If your parents or guardians don't yet trust you to have access to material that you may not share with them, then you are not yet in a position to become an admin. This is much more likely to be true of younger minors than those near legal age.
Unfamiliar content issues
An administrator may choose not to deal with a particular issue simply because he or she does not have the relevant background to address it. For example, an administrator who is not well-versed in higher mathematics who is closing AfDs may choose to skip over an AfD relating to a topic in vector calculus. It does not matter whether the reason is that the administrator is in high school and hasn't yet studied vector calculus; is 60 years old and has forgotten all of his or her vector calculus; or was a humanities major and never went near vector calculus. Using good judgement about what issues one should handle, and what issues one should leave to someone else to handle, is a fundamental skill for all administrators of any age.
A closing word
Although the contents of this page may sound alarming, they are not meant to be. As long as an administrator has the necessary maturity and experience—which is hopefully the case for anyone who has passed RfA—most administrator actions can be handled by administrators of any age. But everyone should utilize good judgement in identifying the few that should not.