The vast majority of my clients grew up speaking a language other than English. They all now speak English, and for a multiple of reasons wish to ‘lose’ their accent.
The process of learning to speak English like a native-speaker is better conceived as acquiring rather than losing an accent. If your mother tongue is Spanish, you’ll be speaking English with your natural vowel sounds, rhythms and stresses. These can never be taken away, nor should they. Your ambition should be to acquire the additional skill of mastering an English accent. With effort and concentration you can master its vowels and rhythms and with mouth gymnastics you will even conquer our consonants!
Just as walking in someone else’s shoes is a disconcerting experience at first, so it is with speaking with an English accent. Expect the process to confound, contort, and confuse. But with practice, patience and plenty of repetition-tition-tion-n-n the shoes you’ve acquired will give in to their new feet, and as well as your native accent you will be the proud owner of a sparklin’ new English one.