Another of the toughest cleaning jobs to tackle and particularly difficult if a bathroom has been neglected or not cleaned regularly.
The first course of action is the most obvious, tackle the effected area with a good scouring pad and some neat bleach (always be careful using neat bleach, where protective gloves and only use in a well ventilated area.) Once all the loose grime and staining is removed rinse the area clean and allow to dry or buff dry with a suitable cloth or towel. Take thick neat bleach and a roll of kitchen towel.
Scrunch the paper towel up and push it into the effected area (e.g. mouldy sealant where bath or shower tray meets tiles) then soak the towel in neat bleach until completely sodden. This forms a mouldable lump of bleached towel. Leave the towel in place for 24 hours (12 might do if 24 is too long) and remove the kitchen towel. Rinse clean and wipe with a suitable cloth and you'll find that your mould has disappeared!