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If the ink cartridges cannot be removed because the carriage is obstinately not moving into the 'open' where you can get at the printing cartridges, then you may have to do this:
1. turn Off the printer
2. unplug it
3. reach into the printer, and gently move the carriage into accessible position. (Warning: if the carriage resists moving when the power is Off, do not force it! damage to your printer may result.)
If there is some other impediment to removing the cartridges from your Canon printer, please let me know in more detail why it is that it is difficult, and I will advise and help you further.