Turn off the “last seen” feature on whatsapp 

Have a stalker? You might want to tweak the Last seen function, which shows the last time you’ve appeared online.

To do this, you’ll need to visit Settings > Account > Privacy. You then want to tap the Last seen field and adjust it accordingly. This can be adjusted to Everyone (everyone with your number can see when you’ve last appeared online), My contacts or Nobody.

Bonus tip:  There are a few more WhatsApp tricks in the Privacy section to fight stalkers and general creeps, such as Profile photo adjustments and the About field. Both of these sections can be tweaked so they are viewable by everyone, only your contacts, or no-one at all.