Not sure why you didn't match the lighter colour and continued the shape. I have several 1 inch roundels and happy to send you one. PM me your address if you want it.
Oh.. instead of painting over the roundel you could use a small rag soaked with warm water put on the decal markings for a while. These roundels would unstick themself unless you sealed them with a clear gloss
Masking tape works good as well, press it down over the decal and rip it off fast like a band aid. I know I use this method a lot being an expert at screwing up decals !