No. If it were possible to steal the Grace of an Angel and use if for freely by anyone without specific knowledge or specific capacity, there would be a black market in Grace as Angels were captured by demons and drained for their Grace.
Grace is a type of divine energy related to an angel's being. It's effectively what makes them angels; without it they are mortal. Anna calls its power "pure creation." Removal of grace is considered a great taboo by angels; it is akin to disobeying orders and punishable by a death sentence, or in the very least torture and imprisonment. Uriel is able to take Anna's grace from the oak tree that it created when she fell. In turn she is able to re-imbibe it and return her angel status.
- Angelic power is so great, it would not make sense for demons to NOT harvest Grace from every Angel they come across, rather than stabbing them with Angel blades and moving on. Since the manipulation of Grace appears to be a knowledge unique to Angels, it is not likely such a power could be used by just anyone.
Anna Milton reveals that she is an angel who chose to fall from Heaven and ripped out her grace painfully. Witnesses mistook Anna's grace for a shooting star. Where it landed, in Union, Kentucky, an enormous oak tree sprouted in the space of a year. In conversation with Dean, Anna indicates that given the choice she would not recover her grace, and would remain human. She relishes the full range of emotions that humans enjoy and the choices they have.
- Angels can remove their own Grace forcefully when they fall. It is presumed they can also remove the Grace of other Angels, but it appears to be something not easily done because Angels kill other Angels with alarming frequency during the series, denoting the absorption of Grace is difficult, at best.
Metatron takes Castiel's grace from him to use in a spell to cast all the angels from Heaven. Without it, Castiel is human, although much like Anna he was still able to hear the angels on "angel radio." After living as a human for some time, he kills an angel called Theo and takes in his grace, and becomes an angel again. It therefore appears that grace is not unique to an individual angel, and can be transferred, though Castiel seemed quite unsure whether taking Theo's grace would be permanent, or what powers he would have. The consequences of stealing another angel's grace was later revealed by Metatron, who told Castiel that his stolen grace was fading, and that once it was used up, Castiel would burn out along with it.
- Angels losing their Grace don't revert to their Human hosts. They remain their angelic selves just without power. Grace acts like the fuel Angels use for their powers. But it appears to be a fuel uniquely able to be used by other Angels. However, use of that power is temporary. An Angel who loses their Grace and absorbs the Grace of another can temporarily boost their powers but will burn out and die when they run out of borrowed Grace.
When angels leave their vessels a small amount of the angel's grace remains inside the vessel. Angel Lore says that "the departed shall remain, and the remains shall be the departed."The Men of Letters believed that if the grace could be extracted, it could be used in a tracking spell to locate the angel the grace belonged to.