If you want to delete both if either is true you could write:
If (a == 3) || (b == 4) delete them If (a == 3) || (b == 4) delete them if (a == 3) || (b == 4) delete this //to delete a
and if (a == 3) || (b == 4) delete that //to delete bAlso this should refer to the temporally closer element, so your choices are backwards.
Please don't ask what if there's four. Very few (if any) natural languages have more than 3 tiers of demontrative pronouns, so computer languages shouldn't -- if they're using ideas natural language to be more readable. They would use identifiers or numeric subscripts instead.