To remove the action column you can set thewidth: 1
in the columns config:
{
id: 'action',
header: '',
width: 1,
align: 'center',
}
Please check the example: https://stackblitz.com/edit/vitejs-vite-xaoxjhav?file=src%2FGanttComponent.jsx
As for adding the columns with custom icons if you use Svelte Gantt you can do it with the help of cell property of the columns config:
const columns = [
{ id: "text", header: "Task name", width: 220 },
{ id: "assigned", header: "Assigned", width: 160, cell: AvatarCell },
{ id: "start", header: "Start Date", width: 100 },
];
The result will look like this: https://docs.svar.dev/svelte/gantt/samples/#/grid-custom-columns/willow
But if you use React Gantt unfortunately now React Gantt doesn't support this functionality.