It is not possible to disassemble the caravan, I get the error message, "There are currently too few employees available for this task."
There are 2 people assigned to the caravan, the 1st is on the road and the 2nd person is in the caravan (not doing a task).
The level of these people is higher, so that looks good.
The only thing I can see is that I recently changed the 2nd person from caravan: (This employee was recently assigned to the caravan)

Caravan dismantle not possible
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Hey,
any employee with the relevant level can dismantle the caravan, it has nothing to do whether they are assigned to it or not.I checked your case: You require one employee. The caravan is at your headquarters but the employee is at the fairground in Eindhoven. He cannot dismantle the caravan because he's in a different location.
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Thank you for your time mate, I totally missed that one…