Anyone can rename the channels they belong to, unless the System Admin has restricted the permissions to do so using advanced permissions.
Select the channel name at the top of the center pane to access the drop-down menu, then select Rename Channel. You’ll be prompted to provide two pieces of information:
Channel display name: This appears in the Mattermost user interface.
Channel handle: This is part of the channel URL. You can also change the channel handle when renaming a channel, but changing channel handles may break existing links.
For example, for the following channel,
https://community.mattermost.com/core/channels/ux-design, The channel display name would be
UX Design, and the channel handle would be
Tap the channel you want to rename.
Tap the More icon located in the top right corner of the app.
Tap View info.
Tap Edit Channel.
You’re prompted to provide three pieces of information:
Name: This appears in the Mattermost user interface.
Purpose: (Optional) Used to describe the channel’s function or goal.
Header: (Optional) Used to include information relevant to the channel, such as key contacts or document links.