Erasure poetry is a genre of "found art" applied to poetry creation. The principle of this genre of found poetry is that the poet comes across or selects a written text, thus "finds" it, then erases words around other selected words, which will create a poetic expression.
Thus an erasure poem is the result of this found art process.
To create an erasure poem, select or come across a written text. Look it over or read it over. Select words that express a poetic feeling, experience, sensation or thought that you have in mind or that comes to mind as you scan your found art text. Now, erase the other words of the text that do not participate in the expression of your poetic creation. This will then be an erasure poem. Selected words may be left standing where they are on the page, in situ, or they may be arranged on a new page into lines and stanzas.
Using the "found" text of this answer, we might create an erasure poem here for an example. I've mentally "erased" all words but these, starting from the top line and accumulating words downward. I've taken them out of in situ and arranged them in one three-line stanza.
EXAMPLE ERASURE POEM
found creation comes across words
erasure process sensation mind scan
participate creation poem recast
An erasure poem is a poem created by erasing words/phrases from something that has already been written, creating a new work of art. You just take a page or section from a magazine, a book, a newspaper, a website, etc. and cross out the words you don't want. Here's an example from page 123 of Auntie Maime:
Aunt Mamie Talking About Supper
The house considered playing hooky.
That’s what they would say.
But at roll-call a slight pause would look
over by the school grounds at noontime
when shade behind building, not being important
had practically undoubtedly returned
certainly to her tomorrow would
just saunter in after America.