To get tree sap off the bottom of your shoes take some rubbing alcohol and dab some rubbing alcohol onto the tree sap on the shoes.
Then allow the rubbing alcohol a minute or two to dissolve the tree sap and then take the rag and put some more rubbing alcohol on the rag and then wipe the shoe with the rubbing alcohol again.
The rubbing alcohol should remove the tree sap from the shoe as it dissolves it.
You can also use some acetone based nail polish remover to clean and remove tree sap off the bottom of your shoes.
The acetone based nail polish remover will easily dissolve the tree sap as well and make it easier to remove from the shoes.