Previously in the game I've been playing, I had accrued too many IPs (insanity points) through game play, and had spent experience (per p. 237, core rulebook) to remove them.

This is especially necessary for my character, as Psykana Templar, in case anyone wondered why I felt the need to do so.

Per the GM in my game, this experience spent, is simply removed, and not counted for my career total.

Then I read recently p. 24 in the Ascension book, wherein the system to create Ascension level characters, players have the option to rid the character of some of their IPs prior to finishing their character. This refers back to chapter one in that book, p. 12, which includes the system of spending experience to remove IPs.

It also shows on p.12 the allowance of sacrificing characteristics for loss of IPs or CPs (corruption points), and trading CPs for IPs.

The question for me is this:

Does this then allow for experience to be spent to remove IPs & CPs, from the original 13k experience of a newly created Ascended character, or only for the use of the initial 500 experience, from rank 9, for this purpose?

The important fact here is if you can use some of the original 13k experience to remove IPs/CPs, then would those experience expenditures be counted against that characters total XP? And then should one always track experience for removal of IPs or CPs for career purposes?

I think you need to contact FFG to get a good answer here (link at the bottom of the page). Personally I'd be inclined to let XP spent on removing IP/CP count towards rank advancement as to not punish the character doubly, but that's just a house rule so...

As I said on a previous occasion, XP spent is XP sent !

So all XP spent count toward Rank.

Don't see why it wouldn't count as per the RAW. There is no prerequisite that I remember about what you have to spend your xp on to advance in rank, as long as it's spent.