Yes it's OK to remove your impacted stool with your finger.
Doctors will sometimes put on gloves and use their fingers to remove some peoples impacted stools or feces when they have a bowel blockage.
In more severe cases surgery may be needed to remove the impacted stool but usually manually removing the impacted stool or feces with your gloved finger will work just fine.
When you have a bowel blockage you'll have trouble pooping or may not be able to poop at all and may have stomach cramps, abdominal pain etc.
The most common symptom of having a blockage in your bowels is abdominal pain that comes and goes and is crampy feeling.
Some other symptoms of a blockage in your bowels are constipation that won't go away, swelling of your abdomen, loss of appetite, vomiting and an inability to pass gas or fart or even the inability to have a bowel movement when you need too.
Sometimes using laxatives or using an enema is enough to get your bowels moving when you have a blockage in your bowels and in some cases the blockage in your bowels may require manual removal of the feces that are blocked in your bowels by a doctor.
So if you can't get rid of the blockage in your bowels within a few weeks then you should see a doctor because if the blockage in your bowels is left untreated and the poop is not removed from your colon or bowels then it can back up enough to cause death in some cases.
So always see a doctor if home treatment for the bowel blockage doesn't work within a few weeks.