Have you seen a therapist and tried medication? Is this something you want to do for a career, or is it just a job for the time being?
Guilt is very common with ADHD. It has ruled my life. I don’t think you can get rid of it, but just learn to live in a way that you don’t do things that make you feel guilty as often. Therapy and especially medication can help, but you often have to try many therapists and many medications before finding the right match. The other thing is finding a job that is best suited for your skills, where organization is not that important, etc.