I made this account 5 years ago and have been flattering back and forth but I've got a few achievements however I'd like to start everything from scratch as I now have new found love for the game and never actively tried to play subeta 'properly' ... and want to aim for all achievements again properly ?

No there is no way to reset an account. Per rules you can only actively play one account. The only instance in which you may have another is if your 1st is frozen and you wait a full year before making another. Other than that specific situation, there is the risk of losing the newer account.

the closest thing to "starting over" would be giving away all your pets, items, and sP, but any progress you've made in collections and achievements would of course remain. i can't really see the benefit of this, though; you can always start/continue working towards whatever goals you have at any time.