remove a 25 year old kitchenaid dishwasher ?

First if its at side of the kitchen sink the check where it drains into, either in the sink waste or it's own waste stand pipe. pull it out when ready to move it.
Find out where the water feed pipe is, is it connected to the kitchen tap cold feed? if so and it has a blue or whatever type appliance tap turn it off , if blue I think handle across the pipe shuts it off in line with the pipe is on. If you can't see it then it's obviously at the back but the pipe from this feed to the machine should be a flexible pipe which allows the machine to be pulled out for repair. Aso where is the power switch it's pluged into? Find that first before having any water flowing around. As long as you are able to turn the water off to the machine you should be able to ease it forward and disconnect the water pipe.
I have never seen one what I call 'Hard plumbed' or fixed plumbed if you like. Just be careful where electrics and water are they don't mix. Best disconnect at mains switch trip on MCB's the one that feeds the kitchen.

Nobby
September 2008