Help how do I fire a contractor in Texas

[Yuxi Li]

I just bought a house in Texas needing some renovations and as a newbie I hired a nightmare contractor to renovate my two bathrooms. They are not GCs but licensed plumbers but I didn’t know any better at the onset of all this and hired them to do a full bathroom remodel. 

They initially hired a horrible subcontractor who did all the work wrong and I had to go up the chain until they finally admitted fault and agreed to redo the shoddy work. Now with a new guy the work is slightly better but my tile floors and very uneven and seeing as this was their attempt to fix the shoddy work I don’t trust them to complete the job anymore. Furthermore they initially quoted me 3 weeks completion via text and now it’s been over 6 weeks and not even the one bathroom is complete. I paid 25% of the cost of renovating the first bathroom and want to fire them. How do I do this legally? And can I somehow prevent them from filing a mechanics lien since I will need to hire someone else to fix everything and repurchase materials like tile?