Hi,
You can try this by clicking on each column with the property setting "show tooltip" --> true, and set it to "false". Then you have to select the Datagrid and set the property "HoverStyle" to 'No'.
To remove the small tooltip that appears on the caption of a table in a Mendix application, you can use CSS to target the specific element and hide the tooltip. Here's an example:
.mx-datagrid-caption .mx-caption-tooltip {
display: none;
}