The ability for the leader to remove individuals from war has been requested and discussed many times. Unfortunately, there are pros and cons to this idea. But those are all laid out in other threads
While I know alliance members are needed, what you really need are GOOD alliance members. People may have different opinions on what a good alliance member is (talks a lot, trains, hits the Titan, etc.).
My personal opinion of a good alliance member is someone who puts the alliance before their own personal game (Uses war flags, hits the Titan even if they don’t like it, follow strategy…). This may or may not be the opinion of your alliance leaders, though.
Since there’s not much that can be done about getting these players out of war, I suggest your leaders decide what a good alliance member is and get rid of those that don’t match your expectations.
EDIT: Another option may be for the active 8 members to identify a solid alliance that can take all of you as a package. This worked well for a group of 6 that were in a similar situation. We talked, discussed expectations and basic personalities. Both groups liked each other and they joined our alliance. They’re now a respected part of our alliance - Using all war flags, hitting the Titan and not worrying about the stress they used to face getting good recruits.