Sheril, welcome to Wikitree. Here we have only ONE tree. Not your tree or my tree. If the ancestor is the same, you've probably met a cousin. You should NOT create a new profile for the same individual.
If it turns out they aren't the same person, then you can detach your ancestor by using the links of relatives on the right side. On the next screen go to the very bottom to unlink the profiles.
As Virginia says you cannot / should not add profiles for individuals born before 1700 unless you are certified to do so. Because those born so early have usually thousands of descendants and, thus, many people interested in them, there are higher standards for documentation than for your near relatives (parents, grandparents, children) about whom you might have personal knowledge.
For these early profiles you will need to search land and tax records, probate and parish records, etc. Ancestry or other online trees are not sufficient--they are often incorrect and prone to mythology.
Have fun researching and discovering more about your family! Let us know if you need further help.