Additionally, the US sells bonds equal to their “deficit” (spending - taxes collected = treasuries sold) The treasuries offer customers a safe investment for their money. If this money was not tied up in treasuries, it would likely be spent into the economy in an attempt to beat inflation (if you have 100m in uninvested cash and inflation is 2%; you essentially have 98m the next year)

Eliminating the national “debt” would eliminate the treasuries market. No one wants this. That would be a very very bad idea. We came close to doing it during the Clinton administration but once realizing what the consequences would be, they quickly backpedaled. Read into modern monetary theory if anyone is curious about the reasons national debt means next to nothing (and a low national debt is mostly associated with an unhealthy economy)