In your Relationship between the two, you should have Cascade Deletes turned on.
Then you make the Delete query from the One side table only.  The related records
in the Many side will be deleted automatically.

Tom Lake

You need to be sure you only specify one table in the DELETE clause. In the
query grid, there should be one or more fields with "From" and one or more
other fields with "Where" - select the * pseudo-field from the table from
which you want to delete records in the FROM column, and put any fields from
the other table in the WHERE column(s).

The SQL view of the query would resemble

DELETE TableA.*
FROM TableA INNER JOIN TableB
ON <whatever>
WHERE TableB.field = something

If this doesn't help, please open the Delete query; select View... SQL; and
post the SQL text here.