Most of the time you would never need to remove the optics from your OTA. However, if the scope is old and dirty, the corrector plate broken, you want to line or paint the inside of the tube, modify the tube, etc. you will need to know about taking out the corrector plate, primary and secondary mirrors.
Since the overall OTA design has changed little over the years, much of the information below is general and covers many OTAs.
Most of the basic information is contained in other Knowledgebase articles or in the Celestron online archives. Outside sources covering rebuilding the optics are also useful and are given last. Here are the links for relevant topics:
Demounting the optics
How do I align my Schmidt-Cassegrain telescope’s (SCT’s) corrector plate and secondary?
Which screws are safe to remove for mounting an accessory finderscope on my Celestron Schmidt-Cassegrain telescope (SCT)?
SCT Corrector Plate Removal
Tuning up the NexStar5
Disassembling a Celestron C11 Optical Tube Assembly
Our Upgraded Celestron-11
C11 SCT Disassembly
NOTE: Opening the OTA will void your Celestron warranty.