The ultimate church promotion, about removing one’s identity as it were? (12)

'the ultimate church promotion' is the definition.
(being canonised as a saint)

'about removing one's identity as it were?' is the wordplay.
I cannot quite understand how this works, but
'about' could be 'on' (as in a book 'on' a certain topic) and 'on' is located in the answer.
'one's' could be 'is' (Roman numeral) and 'is' is located in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?