On mobile, your only option to remove someone from a channel is using a slash command:
Open the Slack app and navigate to the channel from which you wish to remove someone. Type “/remove @ [member]” in the message field. Type in “/remove @ [member]” to remove a member. Devon Delfino/Business Insider
Hit the paper plane icon on an Android or “Send” on an i, and phone.
If you’re the owner or administrator of a Slack team, you can easily remove a user from any channel using your computer, phone, or tablet. If you’re using Slack on a computer, sign into your workspace, and then click the channel in the left panel.
This begs the query “How do I remove someone from a Slack channel?”
When you remove someone from a channel, Slackbot will notify that person. Open the channel you’d like to remove someone from. Click the cluster of profile pictures in the top right. Find the person you’d like to remove and click their name.
How do I remove someone from a Slack workspace?
If you’re looking to remove someone from a workspace instead, you’d have to deactivate that member’s account. Open Slack and select the channel from the left sidebar. Click the person icon (“View Member List”), located just below the channel name . View member list.
How do I remove a member from a channel?
Manage channel members Click the cluster of profile pictures in the top right corner of a channel to view a list of members. Search for and select the person you’d like to remove and click on their name. Click Yes, remove them to confirm.
Click the cluster of profile pictures in the top right. Find the person you’d like to remove and click their name. Below their profile information, click Remove from [channel name]. Click Yes, remove them to confirm. Tap the channel you’d like to remove someone from.
How do I find members in a Slack channel?
If you’re using Slack on a computer, sign into your workspace, and then click the channel in the left panel. Click the icon that looks like a cluster of profile photos at the top-right corner to open the member list.