By default, the column header of the grid shows the field type icon for each field. This also applies to the filter and sort buttons. To hide these icons, follow the steps below:
Go to the Styling & Customization section.
Turn off the Show field type icons toggle.
This setting will apply to all tables in a given portal where field-type icons are visible.
Tip: Field labels normally use the title configured in the child form. A title set for a custom preview field can override it in the grid, filters and sort menu. See custom preview field titles.