how do i remove the slashes from my prefix's when ever i do it in the permissions file, the plugin fails

here is my permissions.yml file:
https://pastebin.com/hCUP2L1E

Try to add your prefix between ' '

options:
  prefix: '&4[OWNER]'

Unfortunately PermissionsEx is currently unmaintained and no further updates are planned. Because of this, all pull requests are being closed. If you are looking for an actively maintained permissions plugin, take a look at LuckPerms. It is compatible with major server platforms and can import data from PEX.