Best way to reduce synched data

[TonyThai]

Dear community I need some advice. 
There are almost 2,000 customers in the Store added by cashiers over a few years, there are almost 40 000 receipts in the Store.
The POS devices (Android tablets) of cashiers are synching info for 2-5 min on each signing into the system.  
I'd like to reduce the synched data to rid of old sales data, what is the best way:
1) Malually delete all "customers" from back office. But receipts will be still there. 
or

2) Open the new store in the back office.
The question is, will the new store sync old data from the past?

or 
3) To open a new account at Loyverse with importing Items.