Which bit are you stuck on?
First you need to undo the footpack to the point of it being around as loose as it was when it was new (it doesn't really need to be this loose, but it makes it easier). Then slide the bits off of the end of the bar.
Now, look on the "inside" of the footpack, where it meets the bar. There's a little lever there which should easily pull upwards towards the bar… There's now nothing holding the footpack onto the bar, but if it's been there for a while/ through lots of bad weather then it may still be pretty stiff!
If you're intending putting them back on again and you don't have the instructions I'd also suggest making a note of where the footpack sits on the bar- there are numbers on the underside of the bar 🙂
If you still need instructions email me and I'll send you a link 🙂
/Halfords guy for the past 6 years :p