Estradiol Valerate Injection has a metal ring which is intended to keep the rubber stopper in place. Do Not Remove the entire metal ring. Only remove the top cap or metal cover over the center of the vial and push your needle through that rubber cover after wiping with an alcohol patch. This is a sterile product and if you are removing the entire rubber cover, you break sterility and risk giving yourself a contaminated injection.
Having said that, look at the vial. Does it say Multidose or Single Dose ? If it says Multidose, you can puncture the rubber cover a few times, using sterile technique, but you should finish the vial within 30 days or whatever the maker states in the instructions. If the vial says single dose, it is designed for one puncture and to discard the rest, whether you use it or not.
Your doctor, nurse or pharmacist should have given you instructions on how to give yourself an injection.