I accidentally poked my finger nail with a rusty metal between the skin and nail, i removed most of the top of the nail there are no scratch or blood, i haven't had a tetnaus shot since childhood, am i safe?

If you cleaned the area thoroughly your risk would be low for tetanus, however we strongly recommend people use this kind of injury as an excuse to update their tetanus shots (every 5-10 years) so they are protected for the future, so I do urge you to get a tetanus booster soon, & see Dr if wounded area has excessive redness, pain, or drainage

Define safe ? Any break in the skin can allow tetanus spores to enter /establish infection & lead to tetanus. Some wounds are more likely to than others, like working in dirt/landscaping/etc. . If nothing else this is a good time to get a tetanus booster. Make sure the wound is cleaned and monitored for infection by any germs.