what people dont realise is although US "owes" other countries $30trillion+
other countries "owe" the us substantial amounts too

an easy option is 1-for-1 cancelation of linked debts between countries

EG if japan hold $1.1trill of US debt. but japan has more then $1trill separately owed TO the us.. they can cencel each others debt thus bring both sides debt totals down

take it one stage further
if japans high DEBT amount of $10trill is owed to multiple countries. the US can do a deal where if the UK cancels its debt with japan. the UK can cancel its loan to the US.
and the US can then further cancel its loan to japan. as a 3 way debt reduction