You can type on a PDF using one of several different options depending on the device you're using. All of the programs listed in this article are available for free, and some methods are built ...

In most cases, however, drawing boxes over text in a PDF just adds the boxes—it doesn’t delete the text underneath them. Someone who would like to extract the text beneath the obfuscation can ...

such as adding new text boxes that overlay the original text in the PDF, using the pen tool to draw over the text with your chosen color, or highlighting the text by applying a translucent color ...