How do I find a Sim that was removed from my household?

@liseylooloo     Hi!  I believe using that "remove from family" cheat places the sim into the "hidden households" category which means you won't be able to see her without using a mod such as MCCC which gives you the option to unhide hidden households using the mailbox MC Cheats menu.  Do you have the MCCC mod installed in your game?  If so, there is an option to summon a sim by clicking on the mailbox and selecting the MC Cheats menu then the Sims / NPC Households Cheat option.  This will work pretty much the same as if your sim had invited her.

If you're not using the MCCC mod, there may be other ways to find her.  I'm guessing this female sim still appears in your played sim's relationship panel and when you click on her thumbnail, there is no option to "invite to hang out".  Is that correct?  If she's not in that relationship panel, it likely means she has been culled from the game.  If she does appear in the relationship panel, then she's still in the game, just likely hidden.  If you don't have the invite option, it could mean that she is unavailable (at work or sleeping or something like that)  OR  she may be in the neighborhood.  The easiest way to find her, if she's in the neighborhood, is to click on your played sim, look for the actions menu and select form group.  If she's available in that menu, click on her thumbnail, click the check mark to add her, and then click somewhere on the ground to have the group "Go here together".  She should then walk over to the area you selected. 

If she's not available to add to a group,  you might be able to use the phone and the social menu to invite to hangout.  So if the above doesn't work, perhaps you could try that.

I sort of feel like I said "if" way too much but I'm just trying to be thorough.  Please come back and update if any of these worked for you or not.