If you want to remove the colorbar, you can set the ColorbarVisible property to 'off':
h = heatmap(magic(5));
h.ColorbarVisible = 'off';
Alternatively, use the colorbar command:
heatmap(magic(5))
colorbar off
To turn off the grid lines, you can either set the GridVisible property on heatmap:
h = heatmap(magic(5));
h.GridVisible = 'off';
or use the grid command:
heatmap(magic(5))
grid off
Heatmap does not provide any control over the outer border around the outside of the heatmap, or the color or thickness of the line, so if you want to change those things you will have to switch to a lower-level function like image or surface.
