The 29-year-old, though still on Facebook, removed his Instagram and Twitter presence on Sunday (AEST) after screenshots emerged showcasing the view from the driver's seat of his car.
Dennis captioned the post: "Day 34 - cracked and left the house. #covid19 can suck my ass and so can #quarantine."
With fans understandably disappointed in his actions amidst the coronavirus pandemic, Dennis took it upon himself to address their displeasure directly.
"Or I could show the reality of how sh*t the situation is and not be one of your beloved drones who show their 'perfect world' as an elite athlete. Which one would you like - real or fake?," said one reply.
"Imagine if everyone lived by your ideal world that we can't speak our mind and show our emotions," said another.
Spain is one of the worst-affected victims of the virus, totalling more than 20,000 deaths, with one of the strictest lockdown measures in the world.
The Team Ineos rider had been training indoors via online platform Zwift before the recent outburst, the first since his sudden exit from last year's Tour de France.