Unfortunately there is no way to completely eliminate unsolicited emails, phone calls, texts and junk mail, but you should be able to significantly reduce it. Companies should not email people who have opted out using the Email Preference Service (EPS), postal mail people who have opted out using the Mail Preference Service (MPS), or call people who have opted out using the Telephone Preference Service (TPS). However, not all companies follow these rules and if you subscribe to a mailing list with the company directly, they are allowed to cotnact you.
There are a number of companies, including Acxiom, Callcredit Marketing Solutions, Dataforce, Eclipse Marketing, Equifax, Experian Integrated Marketing, GB Group, Indicia, Occam, Transactis and Data Locator Group (DLG) that sell their contacts database to other companies for marketing. These other companies should check the opt-out lists held by the services mentioned above and not contact you, if you are on the list. So opting out via EPS, MPS and TPS should reduce the junk and contact you receive. You can also contact the companies that sell your data and ask them to remove you from their databases.
Doing all this can be quite time consuming, but thankfully there are some websites that make it quicker, and easier, for you. StayPrivate.org will register you with MPS and TPS at the same time. ALLOW will register you with MPS and TPS at the same time, and re-register you every 4 months, so you don't have to keep doing it. ALLOW also emails the companies I mentioned above, on your behalf, and asks them to remove you from their database. However, ALLOW asks you to opt-in to receive marketing from them, although they say they will share any money they make, from your data, with you. I will test that and write a full review another time, but this post is about opting-out. On the ALLOW opt-in page, you choose the topics you are interested in, as well as the ways you are willing to be contacted (direct mail, email, phone etc). Presumably, if you don't tick anything, you can use them to help you opt-out, without actually opting in to anything.
You need to register with the Email Preference Service (EPS) yourself, as StayPrivate.org and ALLOW can't do it for you.