Is it permissible to retain offensive terms in forums that describe some famous people as immoral and disobedient as "fasiq" (transgressor/wicked), "mujrim" (criminal), or "khabith" (malicious/evil), or must they be deleted?

If a person is openly defiant in their immorality and depravity, such as those who engage in dancing (for illicit purposes) and proponents of evil, then there is no sanctity for them, and it is permissible to mention their true state for a legitimate Sharia-compliant interest, such as warning people against them. This is what is known as "there is no backbiting for an open transgressor." However, this does not mean exceeding limits by mentioning what Allah has concealed about them, or what the speaker has not verified.

Mentioning the transgressor for what they are is part of thebid-obligatory advice to warn people against them. The intention behind this must be seeking Allah's reward and offering sincere advice, not defamation or schadenfreude. For anyone who hesitates about the realization of a benefit from doing so, it is more prudent for them to prioritize safety and not delve into it.