You need to turn on cascading deletes in your relationship definitions

I don't follow entirely, but you could create three separate delete queries,
each of which picks its criteria from the appropriate
[Forms]![OneOfYourForms]![AControlOnThatForm] (each would refer to a
different form/control that contains the primary key of the record to be
deleted) so that it deletes the correct record from the correct table. In the
Click event, the call for the queries would look like this:

Private Button1_Click()
 DoCmd.SetWarnings False 'hides confirmation messages from user
  DoCmd.OpenQuery "Query1"
  DoCmd.OpenQuery "Query2"
  DoCmd.OpenQuery "Query3"
 DoCmd.SetWarnings True
End Sub

If these are linked tables, you could simply turn on CascadeDelete for the
relationship, and then when you delete the "one" entry, the "many" are
automatically deleted.

I am with Brian on this: cascading deletes can result in a massive loss
of data with no road back. In fact, what I generally do in this situation
is along the lines of:

 ' this is going to be used a lot
 sqlWhere = "WHERE RecordID = " & format(me!recordID,"0")

 ' get an estimate of the likely damage
 wRecordsAffected = DCount("*", "TableOne", sqlWhere) + _
   DCount("*", "TableTwo", sqlWhere) + _
   DCount("*", "TableThree", sqlWhere)

 ' give the user a chance to withdraw
 If vbNo = MsgBox("You are about to delete " & wRecordsAffected & _
   " lines of data. Are you sure?", vbYesNo, "Last Warning) Then
   Exit Sub

 End if

 ' change the question and make really sure
 If vbYes = MsgBox("You are about to delete " & wRecordsAffected & _
   " lines of data. Back out now?", vbYesNo, "Very Last Warning) Then
   Exit Sub

 End If

 ' okay then, can't say we didn't try
 ' execute is a much safer method than all that setwarnings stuff
 db.Execute "DELETE TableOne " & sqlWhere, dbFailOnError
 db.Execute "DELETE TableTwo " & sqlWhere, dbFailOnError
 db.Execute "DELETE TableThree " & sqlWhere, dbFailOnError

Hope that helps

Tim F