1. First, download and follow Adobe.

? Acrobat xpro10.1.2 will display a PDF virtual printer, as shown in the figure below, and then go to the next step.

2. Second, select the PDF printer, and then click Properties.

? Under the Paper/Quality tab, select the black and white option, as shown in the figure below, and then go to the next step.

3. Then enter the file name to be saved in the pop-up window, select the saving path, as shown in the figure below, and then enter the next step.

4. Finally, after setting, click Save, and the pdf file will be converted to black and white, as shown in the figure below. In this way, the problem is solved.