You may need to remove the sump cover
Undo the fixings - use a 10mm socket and a screwdriver
Don't forget to place a suitably sized receiving tray beneath
Using a 19mm spanner or socket, carefully remove the sump plug and fully drain the oil.
When the sump has emptied, wipe clean the sump plug area with a paper towel and fit a new sump plug and washer
Find a Haynes product for your Mazda:
Search by registration mark
Search by make & model