Desechable translates to "disposable" or "throwaway". It's an interesting word because it's not commonly used in romantic contexts in songs, making its appearance here quite striking.
In "Atrévete A Olvidarme," the singer defiantly tells his ex, "Pa que veas que este amor no es desechable" (So you can see that this love isn't disposable). He's asserting the lasting value and significance of their relationship, challenging her to realize that what they had isn't something she can easily discard and forget.
"Atrévete A Olvidarme" is a defiant breakup anthem from Banda Los Sebastianes and Los Bisnietos de Sinaloa. The singer is done arguing with a partner who only seems to open her mouth to fight, so he tells her to leave if that's what she wants — and dares her to actually try forgetting him.
Rather than begging her to stay, he flips the script: he's confident she won't find kisses like his anywhere else, and he even gives her "a couple of days" to come crawling back, sure she'll realize on her own what she's about to lose. It's classic banda swagger — heartbreak dressed up as pride, punctuated by a shoutout to the band itself and their trademark brass-driven energy.