SIMS 4 - My Sims Friends in household and wont leave, HELP!!

Type Ctrl+Shift+C to bring up the cheat bar. Type in testingcheats true and press enter. Shift click on the friend and select reset Sim. Then they should leave soonish. 

Hope this helps!

Thank you for this, however they have not moved ☹️

Could you check if you maybe are still affected by this issue: http://sims4.crinrict.com/en/2014/12/visitors-wont-leave/