Can't remove the brackets around the usernames

I use PermissionsEx with Essentials and EssentialsChat, I edited the brackets in my Essentials configs, it didn't work.

Here are my plugins: WorldEdit, Essentials, AutoBroadcaster, WorldGuard, NoCheatPlus, EssentialsXMPP, EssentialsProtect, EssentialsChat, EssentialsGeoIP, EssentialsAntiBuild, PermissionsEx, mcMMO, Vault, EssentialsSpawn, MassiveCore, EnjinMinecraftPlugin, MassiveTickets, MassiveHat, CreativeGates, LWC, PlotSquared, Multiverse-Core, Factions, MassiveBooks, Vampire

Here are my EssentialsChat configs:

############################################################
# +------------------------------------------------------+ #
# | EssentialsChat | #
# +------------------------------------------------------+ #
############################################################

# This section requires the EssentialsChat.jar to work.

chat:

# If EssentialsChat is installed, this will define how far a player's voice travels, in blocks. Set to 0 to make all chat global.
# Note that users with the "essentials.chat.spy" permission will hear everything, regardless of this setting.
# Users with essentials.chat.shout can override this by prefixing text with an exclamation mark (!)
# Users with essentials.chat.question can override this by prefixing text with a question mark (?)
# You can add command costs for shout/question by adding chat-shout and chat-question to the command costs section."
radius: 0

# Chat formatting can be done in two ways, you can either define a standard format for all chat.
# Or you can give a group specific chat format, to give some extra variation.
# For more information of chat formatting, check out the wiki: http://wiki.ess3.net/wiki/Chat_Formatting

format: ' {DISPLAYNAME}: {MESSAGE}'
#format: '&7[{GROUP}]&r {DISPLAYNAME}&7:&r {MESSAGE}'

group-formats:
Default: '{WORLDNAME} {DISPLAYNAME}&7:&r {MESSAGE}'
Admins: '{WORLDNAME} &c[{GROUP}]&r {DISPLAYNAME}&7:&c {MESSAGE}'
Owner: ' {DISPLAYNAME} : &6{MESSAGE}'

# If you are using group formats make sure to remove the '#' to allow the setting to be read.

I also tried without adding anything in group-formats, nothing works.