Are the two being symmetrical part circled in blue the following picture DU bushings ? How could I remove them without the appropriate tool ?
I would try two small screwdrivers or putty knives under the lip and GENTLY pry up. when one side starts to move try the opposite side. Work you way around until there is a gap between the bushings. Insert something soft like a pencil or wooden dowel into the hole and gently tap the bushings out. In my experience these type of plastic bushing are not particularly tight. They can however be fragile especially when the are exposed to strong sunlight or cold temperatures. When it is time to reinstall them they may push in by hand with a little lubrication and a gentle push. If not find some fender washers larger than the bushing. Place the washer over the bushing flange. Put a bolt through the washer. Install the second washer on the bolt, add the nut. Tighten the nut to push the bushing into the shock. Repeat the procedure for the other side.
Press them out from the other side using a threaded bar, buts washers and probably a suitable socket (one on the lip on the back and one large enough on the side shown in your picture so the bush can fit inside it).
Why do you want them out?