Delete the text after the firts line for every cell of the first column of a libreoffice calc file

Hi, I need to d<elete the text after the first line for every cell of the first column of a libreoffice calc file for about 945 rows of the same file, attached a demo of how are looking the cells before and after the needed task.
I will send you the original file on rerquest.
And if possible then teach me how to do that please too.