I've not done it on a Jazz but its not always that easy. If you need to disconnect water tubes from the pump some cars use special connectors and even if simple tubing is used the joint might leak after you replace the pipe. There are ways and means around this if you have a bit of practical experience or willing to have a go.
I think the filler nozzle is separate from the tank itself and pushes into it with a simple rubber sealing ring. The job may be easier if you can find a way of disconnecting just the filler tube . It may then be possible to effectively blast the inside of the tank while its still on the car through the hole left by the filler tube.. Then keep a good flow of water into the tank until all the suspended debris overflows.
The pictures on this ebay listing may help clarify what I mean
https://www.ebay.co.uk/itm/114780458703?Edit. Taking a look at this second hand unit it looks like the washer pump may plug into the side of bottle as a unit using a fairly simple sealing washer. If there is room it may be possible to simply unplug the pump from the bottle leaving complex wiring and pipes still attached to the pump. . This may give more immediate and effective access to clean possible blockages.
https://www.ebay.co.uk/itm/356716373395?Let us know how you get on. Either success, or obstacles that put you off proceeding.
