Will my nose return back to its normal shape when I remove the silicone implant I had put in 4 years ago? (Photo)

It is unpredictable what kind of deformity you will end up after removal of current implant. Based on size of implant and your underlying structures (bone, nose tip cartilages, skin) you will need reconstruction with multiple cartilage, possibly bone grafts. This is going to be much more demanding reconstruction than with implant.A detailed clinical evaluation by an experienced board certified plastic surgeon, a recognized nose surgery expert (who may offer multiple reconstructive options) should be your first step. Good look. 

 It is possible to remove the L. strut silicone implant that was placed previously. As long as there were no other changes made to the nose at the time the implant was placed, then the nose should revert back pretty close to its original shape. Revision rhinoplasty is one of the most difficult procedure to perform correctly in the entire field of cosmetic surgery,  so choose your  revision surgeon very wisely based on extensive experience with the procedure

You have had a solid silicone rubber L-shaped implant for some time. The body always forms a capsule around these implants, many times thin but sometimes not. In addition, the skin has now "expanded" to be more voluminous around the implant. Whether your skin can contract down to your dorsum, and thin down afterwards, is very hard to predict. My suggestion is to consider first having the implant removed, without any further surgery done at the time of removal. This will allow you and your surgeon to assess how well your skin will contract down to your bridge, and also to assess how your nasal structure is beneath the implant. Some surgeons will actually remove some bone when placing an implant to allow a better base for the implant to sit upon. If this was done, your underlying dorsum may be quite different now than you remember it. See an expert rhinoplasty surgeon with experience in nasal dorsal reconstruction for a personalized consultation before formulating any definitive plan.