If you are an Organizer, Co-Organizer, or Assistant Organizer, yes.
To remove a member from your Meetup Group, find them under the 'Members' page of your Meetup Group, click the gear icon next to their name and click 'Remove member.'
When or why to remove someone from your Meetup Group is a tricky question, and it varies from person to person.
The simplest answer is: if a Member of your Group is not getting along with others, or making you feel uncomfortable, then it's probably worth considering.
The important thing to remember is that as the Organizer, it's entirely up to you to decide when or under what circumstances to remove someone.