#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "<p>((?!<\/p>).)*?(TEXT).*?<\/p>"
Local $sString = "<p>1 bla bla <em>bla</em> bla bla</p><p>2 bla bla <em>bla</em> bla TEXT bla</p><p>3 bla bla <em>bla</em> bla bla</p><p>4 bla bla <em>bla</em> bla TEXT bla</p><p>5 bla bla <em>bla</em> bla bla</p>"
Local $sSubst = ""
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm