The idiomatic antonyms of "keep someone in the loop"?

Question

In this thread I realized that 'loop someone in' does not fit in the scenario of inviting someone into a WhatsApp group for an intermittent discussion, and the idiomatic expression should be 'keep someone in the loop'.

But how to express that opposite? For instance, someone is too annoying in the group sending irrelevant messages now and then, and the moderator just removes them from the chat group. Are the following phrases appropriate?

1. leave someone out of the loop
2. cut someone out of the loop
3. take someone out of the loop
4. remove someone out of the loop

Or there are more native ways to talk about it?

Answer 1

Answering your question:

You've got the right idea with your phrases. There isn't a separate common idiom for not keeping someone updated.

1. "leave someone out of the loop" - this is OK, but could imply they were never in the loop, or that you are looking at current members and "cleaning up."
2. "cut someone out of the loop" - OK - cut is a strong word, meaning someone very much wanted X out of the loop.
3. "take someone out of the loop" - OK, and neutral tone.
4. "remove someone out of the loop" - Better said "remove from the loop" - OK, and neutral tone.

Some relevant information:

Keeping X in the loop means to keep X informed with periodic updates.

If periodic updates are in a WhatsApp group, adding X to the group will enable X to stay in the loop.

But other things could keep X in the loop as well, such as someone relaying X information every once in a while, etc. Therefore, if you want X out of the loop, you may need to do more than just remove them from the WhatsApp group, unless the WhatsApp group is the only source of that information.