You cannot edit the price of the NFT that has been put up for sale. You can, however, remove the NFT from the listing and put it up for sale again with the edited price.
If your NFT has been listed for bidding, it should be noted that removing your NFT from being listed immediately cancels all the bids your NFT has received so far. Any person who has placed a bid on your NFT will have the bidding amount returned to their available balance on the GuardianLink wallet.