One dirty solution could be temporary change company_id of some registers using psql.

update account_journal set company_id = 'temp_company_id' where company_id = 'current_company_id';

update account_move set company_id = 'temp_company_id' where company_id = 'current_company_id';

update account_move_line set company_id = 'temp_company_id' where company_id = 'current_company_id';

After that you can change the currency of the company.

At the end you can return to the previous value of "company_id" of the modified registers.

Hi,

Thank you for your solution.

I am getting this error while deleting a paid invoice:

ERROR: update or delete on table "account_move_line" violates foreign key constraint "account_partial_reconcile_debit_move_id_fkey" on table "accoun t_partial_reconcile"
DETAIL: Key (id)=(45) is still referenced from table "account_partial_reconcile".

yea u can go to psql and use command
delete from account_move_line;
and delete all the transactions (ONLY IF YOU DONT NEED THOSE DUMMY ENTRIES)
Then you can change currency.

Thanks @cesar mateo

can i delete those transactions or make it go back to how it is, so i can change the currency?