It's my FIL birthday Sunday so we are having them over today for tea. I made the cake yesterday (a tractor tyre), covered with b/c then fondant. The problem I have is that my writing is terrible and I wrote the Happy Birthday freehand in b/c. Yesterday was a horrible day for me (my old whippet fractured his back while I was putting him into the car to take him to the vets for an operation to have some lumps removed and we had no choice but to let him go) so needless to say by the time I did the cake I didn't really care about it. Today I looked at it and I am pretty embarrassed by the writing - it is really bad even for me- but don't know how to get it off without wrecking the fondant. Fondant is black, sprayed with pearl sheen, writing is white.

No matter what you do the fondant will become shiney.  You might be just as well off leaving it the way ti is OR

cover it w/another layer of fondant - a 'plaque' on which you have already put the message.

You aren't going to get a neat seamless cover up job, so I would go with Kakeladi's suggestion and use a fondant plaque.

Sorry about your puppy :(

Thankyou Kakeladi - I don't know why I didn't think of laying another piece of fondant over the area after removing most of the buttercream, that will actually work great for me. I did think of RI but don't have the time for it to dry enough to then put writing onto it. Thankyou very much.

I'd freeze it for 5-10 min. and pick it off.

Thankyou to all who replied - I cut a strip of fondant and arched it to a semi circle to fit inside the 'rim' of the tyre then cut the ends into snake tongue forks. Placed that over the old writing and it looks like it was always there.