Pros who have to cover their frames at events because of sponsor clash use electrical tape. However most of the time it's because they want to be able to remove it without damaging the paint and graphic work.
Suggestion 1- Go to a signwriters and get some vinyl to cover up what you don't want. Maybe even rename it, put some graphics you would want.
Suggestion 2- (the expensive option). Get the frame stripped and repainted with whatever colour you want.