"The mayor lives here."
Translation:De burgemeester woont hier.
Those sentences are grammatically correct, but there are few scenarios in which you would use them. Even if someone would point at a house and asks who lives in that house, you would still get 'de burgemeester woont daar/hier' (the mayor lives there/here) as an answer, instead of using 'erin' or 'hierin'.
Erin or hierin with 'wonen' is not a valid combination, we use it more to indicate if something is inside of something else, usually a container. 'Wat zit erin/hierin?' (what is inside it/this?). 'Daar zit een appel in'.