What is the yo form of verb decor in present tense?

The verb "decor" is not a standard verb in Spanish. It's likely you're looking for the "yo" form of a verb related to decorating, such as:

* "decorar" (to decorate) - "yo deco ro"

* "adornar" (to adorn) - "yo adorna"

Please clarify what you mean by "decor" so I can give you the correct "yo" form.