What is the monerod command to pop off a certain amount of blocks? Say I am at block 1.5 million and I want to start from 1.4 million instead. What is the monerod command for this?
The command you are searching for on linux called:
./monero-blockchain-import --pop-blocks 100000
and on windows you need to use
monero-blockchain-import.exe --pop-blocks 100000
A detailed howto is on point 4 at this answer from dEBRUYNE.