I created a copy of an item and this is replacing an existent item, but the players continues finding the default item in the containers.
EXAMPLE:
I created a copy from Greater Swordsman Belt and I changed the special properties like an item cost parameters
But the players continues to find the old item with low price
Is possible to remove the items from the game chance?
It is but if you are using a non-template-treasure loot system where the item resrefs are written inside script this will be very difficult to do.
Or is possible to edit an default item without Edit a Copy?
Yes, this is probably easier solution. Basically, you find a resref of the standard item and write it down. Then you make your replacement item in toolset.Now, you rip the *.uti file for your item from the module - you will find it in modules/temp0 and the name of the item will be its resref. And move it into server's override folder.
Now the harder part, you need the GFF Editor Modified (or maybe the default one can do this? not sure) and you need to open the item *uti file in it. There you change the resref of the item to match its standard item counterpart and save it. Also you need to change the file name to match standard item resref too.