var table = MapView.Active.Map.GetStandaloneTablesAsFlattenedList().FirstOrDefault();
if (table == null)
return;
QueuedTask.Run(() =>
{
var tableTemplate = table.GetTemplate("Template1");
//Removing a table template
table.RemoveTemplate(tableTemplate);
//Removing a template by name
table.RemoveTemplate("Template2");
});