Mistakes happen during application, and it's perfectly normal to attempt your paint repair more than once before you get it correct.
To prepare your repair area to be repainted, there is no need to remove the paint. You only need to scuff up the top layer of clear coat that was applied using. Use 1000 grit sandpaper and a cup of water to gently wet sand the area. After scuffing up the layer of clear coat, wipe away any residual dust with a dry cloth.
That's it! You're ready to repaint.
For instructions on how to repaint using aerosol, use the following articles (starting with "Step 2 - Paint The Surface"), according to the kit you have:
• How to Use the Aerosol Spray Essential Kit
• How to Use the Aerosol Spray Preferred Kit
• How to Use the Aerosol Spray Platinum Kit