Institute a "be nice" rule. You don't need to enumerate all, or indeed any, of the things you consider not being nice - that will only lead to the trolls avoiding the specific behaviours you've listed and still being annoying and trollish, but giving a few examples can help give context to the rule.

Then, after a shortish period, suspend or ban them for violating that rule. If you can suspend for a few hours/days rather than outright banning it's better as it gives them a way back if they reform.

Your regular players are happy because the troll has gone so are less likely to quit the server.

Institute a "be nice" rule. You don't need to enumerate all, or indeed any, of the things you consider not being nice - that will only lead to the trolls avoiding the specific behaviours you've listed and still being annoying and trollish, but giving a few examples can help give context to the rule. You also need to include a caveat and "catch all" phase to avoid the case of someone saying "well this behaviour isn't explicitly against the rules". Something along the lines of:

This list is not exhaustive and includes behaviours and actions that a reasonable person would find to be against the general "be nice" rule.

Then, after a shortish period, suspend or ban them for violating that rule. If you can suspend for a few hours/days rather than outright banning it's better as it gives them a way back if they reform.

Your regular players are happy because the troll has gone so are less likely to quit the server.