Iam beginer, I try to create already tab but I can’t remove it
Hey @nfs28794 and welcome to the Infinity Community 
Thanks for reporting your issue.
Okay, so when you’re working in a Columns view in Infinity, you’ll NEED to group them by a certain attribute (Labels, Checkbox, Members, Date).
In your case, you’ve created an attribute ‘Checkbox’, and now your Columns are grouped by that certain attribute.
Hence, you’re not able to delete that specific columns unless you decide to group your Columns by different attribute, or delete ‘Checkbox’ attribute (but we don’t suggest that).
Was that helpful for you, @nfs28794?
Let us know if you have any further issues, please