How do i change a formal dress and make it look less formal?

i have a tube dress,which looks formal.it has two layers,the inner one is black and outer one is purple so the whole dress looks drak pupple.im planning to wear it to a christmas service in church and i dont want to look over dressed.How do i change a formal dress and make it look less formal?
Instead of wearing heels you can wear comfortable flats %26amp; maybe a mini jacket or sweater over your dress will help. Don't use really shiny earrings maybe a casual earring and try not to get too fancy with your hair like putting too much gel to make it shiny or having a lot of hair accessories in there. Hope this helps! Even though, have fun at the party!How do i change a formal dress and make it look less formal?
You can wear flats. Flats make a lot of clothes look more casual. If you wear heels, you are just going to look even more dressed up. Try some bright jewely too. (Not too bright and not those bracelets with the giant stones!)
Wear a shrug or cardigan over it and don't wear anything with high heels--either go for a kitten heel or some simple flats.
Remove nothing! Add casual sweater/jacket/shawl

and casual pumps. And PONYTAIL? You'll look sweet
tie the dress in the back with bobby pins or a rubber band. this will make it look like a top. wear a cute cardigan with it. and also wear it with skinny jeans. i would suggest a black cardigan with black flats or cute flip fops
Definitely wear some kind of cardigan or solid black top (perhaps a nice long sleeved black shirt, so it looks like you have a skirt on). You can still wear heels with your outfit. Just because you are wearing heels does not mean that you getting too dressed up.