Asking for help, I have a few questions about Sims 4.

@Thehiddenreturns Played and unplayed households is the same thing (I think those are the old terms for those tabs?), so yes, the two tabs in manage households. If you only want to delete one Sim in the household, you can split the household so the Sim you want to delete is in their own household, then delete that household that includes only the Sim you want to delete. 

Split Household Tutorial: https://sherigr.com/tutorials/split-household-in-sims-4/

If you want to delete the whole household, you can enter the household in Manage Households and either:

1.  Select them in the list of households and click the red "X" in the top right of their thumbnail:

OR...

2. Open the household and click the trash can in the lower right:

OR

3. In the above screenshot, click the pencil icon and open them in CAS if you need to split the household. (see Split Household Tutorial at the link above if you need it.) Then once the household is split, you can use one of the two above methods to delete the one you don't want.