Take the filling out and wash it but the flavour will still be in the atomiser and depending on what it is may take forever to
vape out.
If its something strong say Fennel Mint Coffee they are all really a pain in the neck to get rid off.
Soak the atomiser in coke overnight - rinse - blow out - dry off - prime and it should taste better.
The best idea is to keep a seperate atty for trying out new flavours, and if you like menthol keep one atomiser just for that as it will overpower most other things you put in it.
You can never have enough atomisers .