error running configure; how do I start over?

[Shinehah-Gnolaum]

I made an error running configure. The first time I ran the line given in the instructions at https://github.com/tesseract-ocr/tesseract/wiki/Compiling#macos It didn't work because the c++ compiler couldn't make executables, it said. The second time I didn't set the environment variables.

How do I start over? Do I have to undo what I've done before I start over, or can I just start over and what was done before gets overwritten?