Cell without cell wall are known as

A cell without a cell wall is known as Protoplast.
Protoplasts are isolated cells produced by removing the surrounding cell wall either by mechanical means or by the use of cell wall degrading enzymes.
It is a biological term coined by Hanstein in 1880 to refer to the entire cell, excluding the cell wall.
Protoplasts are widely used for DNA transformation (for making genetically modified organisms) since the cell wall would otherwise block the passage of DNA into the cell.