Certificates erase

[yoker]

Can anyone enlighten me how exactly certificates deletion works?
Here's the deal: my friend had trigger haste, passive (master) evasion, counter UD. He decided to change UD into cele. Deleted tank, added BD. Now he can't take certs from BD. I believe that he can erase all for 10kk, get new books and change UD into cele but I always that deleted sub doesnt interfere with anyhow with the new one and he can keep both skills - ud and cele. Am I simply wrong or does he do sth wrong?

[Evangelion]

i could just tell you or just paste this http://lineage.pmfun.com/list/skillcertification

[yoker]

lol, I obviously know this page but havent gone yet through it carefully. All clear now. Thanks