Open your image in Adobe Illustrator
Select the image with the Selection Tool
Go to Window > Image Trace
Choose a preset such as High Fidelity Photo or Black and White Logo
Adjust the Image Trace settings if needed
Click Expand in the top toolbar
Ungroup the traced artwork if necessary
Select the background shapes
Press Delete or Backspace
Use the Direct Selection Tool to remove any remaining unwanted areas
Save or export the file with a transparent background