Prune blockchain up to specified height or unix timestamp.
height
curl --user myuser --data-binary '{"jsonrpc":"1.0","id":"1","method":"pruneblockchain","params":[800000]}' -H 'content-type:text/plain;' http://127.0.0.1:8332/
799999
preciousblock
savemempool
bitcoind.app — Bitcoin Core RPC Reference