Clay Bar will not properly work unless the wax is already removed. Many professional detailers do not use dawn because of it's harsh abrasives. The safest way to remove the wax is to use a non or very light abrasive polish. I use P21S Gloss-enhancing Paintwork Cleanser.
The is commercial stuff, but the good stuff. . . I'll post some links to retailer if necessary.
These are paint cleaner/polishes, which contain no silicone or wax. This will restore the luster to your paint and remove any wax or contaminents. If the paint looks good but still feels gritty after hitting it with the glaze. Use a clay bar. Then repolish with a 3M glaze again.
Top of with a carruba wax. I prefer blitz as it does not mess up the trim like other waxes do.