some nice person has broken my windscreen wiper, the motor works ?

I think you are trying to describe the following:

Your car has two wiper arms
One wiper arm has been damaged and is now flopping all over the place
The other wiper arm is OK
You want to temporarily disconnect/remove/disable the errant arm.

It should be possible to remove the errant arm and blade.

The exact method will depend on the exact make and model of car, as they are all different. Unfortunately you decided not to impart this information.

You COULD do a Gooogle search for "Make Model remove wiper arm" - replacing Make and Model with your own info

It can be a bit of a pig as the wiper arm may be reluctant to leave the spindle. Take great care with the paintwork.

If the linkage underneath the bodywork has been damaged - the damaged wiper's spindle moving freely is a giveaway - you will need to consider getting access to the linkage to mend or probably replace. Often a complete pig of a job but again, depends on the make and model. You may get some idea from another Gooogle search, this time for "Make Model replace wiper linkage"

You may also consider searching for enthusiasts forums for your particular make/model of car.

dsfdsf
October 2017

Without knowing what sort of motor you have, and the extent of the vandalism, it could be one of your wiper arm nuts are loose, if not then the motor and linkage, usually under the scuttle panel may need looked at, good luck.

cdc
October 2017