Any wallet on the XRP Ledger can issue their own IOUs.
GateHub strongly recommends only accepting IOUs by trusted issuers, for example GateHub or GateHub Fifth.
In order to dispose of any leftover balances and disable inactive trust lines in your wallet to free up the XRP reserve (5 XRP per trust line), you can send them back to the issuing address via Send payment - INSTANT. Trust lines are set to issuing addresses.
Some IOUs by inactive issuers are populating the XRP Ledger which may pose a threat to less experienced users. See our article about defunct gateways here.
To prevent issues with defunct gateways, we suggest our users remove all trust lines issued to inactive or less trusted issuers, and to disable rippling on any remaining trust lines.
GateHub and other affiliated gateways will always perform a global freeze on the XRP Ledger for delisted IOUs to prevent worthless IOUs from circulating (What is a global freeze?).