Delete records from a table

good day !

need assistance on below.

have two tables as follows;

Master file:Vessel_master
Vessel_code
Vessel_name

main data table:Main
Vessel_code
container_no
size
Voyage
weight

by using above two table have made a query as follows;
Vessel_name:Vessel_master
Vessel_code:Main
container_no:Main
size:Main
Voyage:Main
weight:Main

Have joined "vessel_code" fields of the both tables by join type 2.

by using the query as data source made a form to edit/update/delete data. the problem is, when delete a record by using the form, it will delete the related data in the master file as well, which i do not want.

Appreciate any expert's advise.

brgds
Htadis

Delete records from a table