Presume you mean the long hose. It is secured on the main part of the machine by the piece of plastic with the hook on it (the hook is used to tie up the cable). This is the hose retainer. Just below the hook there is a hole in the main housing with a ribbed button visible in it. Push this button in with a suitable tool at the same time pull upwards on the hook. This should release the hose retainer and the hose can be pulled out (it's just a push fit into the pipe that connects to the main body). When you refit the hose retainer make sure the button is firmly in the hole or when you next wind the cable onto this hook the retainer will pull out.
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