Q: Cannot make formated bootcamp partition come back to Osx Partition

After partitioning for bootcamp, using bootcamp assistant, all working fine with windows 10 installed. I have formated the bootcamp partition using Disk Utility - thinking i was doing it with a pendrive =( - now i cannot make them be one again, the minus button is not available when I click the partition. Screenshots of my disk utility now, it has the Machintosh HD partition with 449gb avaible, and the other called Free Space for some reason, with the 50gb I let for using windows previously

If I try doing it trought restarting and holding CMD + R it gives me the option to install on the 449gb partition, without the 50gb left on the other one.

If i try doing it trought bootcamp assistant, it says it cannot restore my hd.

What should i do?

thanks in advance!