Remove columns from a content type
Columns can be added and removed from content types as necessary. To remove a column from a content type, follow these steps:
To remove a column from a content type
Go to the Content type gallery in the SharePoint admin center, and sign in with an account that has admin permissions for your organization. The Content type gallery page isn't available if you have the global reader role.
Under the Site content type column, select the name of the site content type to which you want to remove a column.
Under Site columns, select the column name you want to remove.
Select the vertical ellipsis to the right of the site column name you selected, and from the dropdown, select Delete. A Delete site column dialog box appears prompting you that this action will remove the column from the content type.
Select Delete to confirm.