free up space by deleting blocks
Depending on your requirements, you can run in prune mode: 

$ bitcoind -prune &lt;max-MiB&gt;


  -prune= Reduce storage requirements by enabling pruning (deleting) of old blocks. This allows the pruneblockchain RPC to be called to delete
  specific blocks, and enables automatic pruning of old blocks if a
  target size in MiB is provided. This mode is incompatible with
  -txindex and -rescan. Warning: Reverting this setting requires re-downloading the entire blockchain. (default: 0 = disable pruning
  blocks, 1 = allow manual pruning via RPC, 550 = automatically prune
  block files to stay under the specified target size in MiB)


see https://bitcoin.stackexchange.com/a/37497/60443