You can drop a bufferpool by utilizing "drop bufferpool" order. It is recommended to check if any tablespace is appointed to bufferpool before utilizing drop order.
drop bufferpool <bp_name>
We should drop the bufferpool named "new_bufferpool".
db2 drop bufferpool new_bufferpool
db2 "select bpname,pagesize,npages from syscat.bufferpools"
You can see that there is only one bufferpool in the rundown and "new_bufferpool" is dropped.