What can I do to better manage my overwhelming sexual desires by my own without a counsellor/psychologist? How can I stop masturbating and stop watching pornography?

It can be hard to stop sexual desires but it is possible. Imagine your sexual desires like a bull. A bull is known to be wild and rarely tame but can be calm but sometimes that bull may be always up an running. To calm the "bull" you have to give it time and try to avoid triggering the bull like avoiding porn and anything sexual. It may be hard but you will definetely heal with some effort.

Distracting yourself with other activities and hobbies will help. Taking up hobbies or charity work will mean you have less time to do the things you're trying to stop doing.

It takes a lot of self control, A LOT! Eliminate anything that could cause triggers to masturbate or watch porn, if possible. Otherwise try to find ways to distract yourself. When you want to do it, find something else to do. Try to move your thoughts in another direction, to something productive. Pleasing yourself to some degree is normal and sometimes needed for your health. :) So you could also moderate it, give yourself how many times and for how long you can do it. There are also support groups to help you with it.

What I did was exchange my phone for a flip phone, and delete all my history so I wouldn't be tempted to do it. I also put a password block on those websites, passwords that I would not remember. The mastrubating problem, I have no idea how to.

Just keep yourself busy and physically active, do sports and anything to distract you on your free time

Focus. Make yourself busy by doing hobbies. You can watch movies. Walk at the park. Listen to music. Read a book. Stay away from everything that triggers you to do those things. This will require effort and discipline but, again, FOCUS.

There is lots of things you can do, exercise can be a great way to stop masturbating as it releases feel good chemicals into the brain just as masturbation does. Distractions like art, reading, talking with a friend all can be helpful. It's just about trial and error and what helps you in the long run. If one thing doesn't work try another

Make goals for yourself to slow down. Do not try to go from all to nothing in one night, because that will make things worse. It may take a month, but steadily limit yourself on masturbation per day or week and Porn videos watched per day or week.

In my personal opinion, masturbating and watching pornography is totally fine. We all are different and our libidos are all different too.

There is no actual good reason to stop masturbating. As far as I'm aware there are no negative side effects as long as you do it in a natural way. It even helps release stress. Instead of trying to stop masturbation take some steps toward acceptance. You should feel comfortable with your body and your sexuality. Learn to love your body. Not only will it lead to improved mental health, it can potentially improve your sexual health and your relationships with others. P.S. Don't overdo it though, just do this according to your sex drive and your desires in general. Also a tip for women: I suggest using your hands or a plain regular dildo rather than vibrators or showers. If you stimulate yourself using a vibrator/shower the stimulation is intense and will make you less sensitive. If you are a straight woman, your partner will not be able to stimulate you the same way a vibrator does. However if you like using things other than your hands to stimulate yourselves that's perfectly fine, as long as you're happy. Live for yourself. :) As for pornography, I suggest treating it the same way you would treat an addiction. Try using the 12 step program.