To set the paragraph indentation to 0, type \parindent=0 before your first paragraph - this will make all subsequent paragraphs have zero indentation. You can change the number 0 to any other number to alter the amount of indentation and you can also insert the same command again ...
17 Numbering paragraphs in latex 7 Numbering of subsections and paragraphs Related 4 Increase indentation of a paragraph 4 Setting paragraph indentation AND vertical space in KOMA class 5 Line break after description label 2 Avoid paragraph new line after enumerate or itemize from package ...