Group conversation

If the group contains anyone that is not an iOS user, the ability to remove may not be available. Also, the group has to be of at least 3 or more to remove. As far as adding, you do not see a + Add Contact under the list of existing group members? What troubleshooting have you tried?

Edited to change the 4 to 3 members.

Standard user troubleshooting steps include restart, reset, restore from backup, restore to factory. The restart and reset will not affect any content on your device.

Restart your iPhone, iPad, or iPod touch - Apple Support

Restore your device from an iCloud or iTunes backup - Apple Support

Use iTunes to restore your iPhone, iPad, or iPod to factory settings - Apple Support

I'm guessing here that you have not experienced this problem in the past? Have you made any changes to the device if it was working before and has stopped now? Have you tried deleting that conversation and starting over again, or start a new group chat with someone else and see if you experience the same problems?

EDIT: One last thought I just had, you indicated there were more than 3 users in the group, how many total people are there? It may be you have exceeded the maximum number in a message? There used to be a maximum number. I don't use group messages that much, so I don't know if this has changed any, but I remember there was a maximum in the past.

No, that is not too many, however, as I indicated earlier, if you have someone that is using a non-iOS device, you may not have the option to remove someone from the conversation. That is a restriction of the other operating systems, and the fact that the message is not an iMessage at that point, but an MMS.

LeslieRN111 wrote:

Yes, the chat includes users other than ios

Then you can't add or remove people, regardless of the number.