The safest (and I think it is the easiest as well) way is to remove the lower dash panel under the steering wheel (a couple of phillips screws), partly remove the flexible hose to the side ventilation opening and get your arm up to (dis)connect the speedo cable.
Pulling the dash cluster may damage the speedo cable that gets pulled out of its position (it can stand some pulling but not too much).
In the W201 you can leave the steering wheel on to get the dash cluster out; there is enough space to get the dash cluster out.

greetingz,

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1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)