They’re probably text objects, however it’s not possible to access their properties. The only way to change them is to get them, delete them frm the axes, and use the text function to put them where you want them by setting the 'HorizontalAlignment'. 'VerticalAlignment', and other properties.
xc = categorical({'A1','A2','A3','A4','A5'});
figure
scatter(xc,rand(5,size(xc,2)), 'filled')
colormap(turbo)
Ax = gca;
xtl = get(Ax,'XTickLabel');
set(Ax,'XTickLabel',[])
yl = ylim;
text(1:numel(xtl), ones(size(xtl))*(yl(1)-0.025*diff(yl)), xtl, 'Horiz','center', 'Vert','top', 'Rotation',30)
.
