When printing with a laser printer, the toner is fused onto the paper at a high temperature, melting the toner particles into the fibres of the paper. Toner ink is tricky to remove because the toner is deeply ingrained with the paper. Applying chemicals such as hydrochloric acid and bleach won't do the job as they would with other kinds of inks. Liquid paper can create an undesirable off-colour look, depending on the quality of paper. A few other simple options are still viable for removing laser ink from paper.
Grab the problematic paper as soon as it has finished printing. The ink will be much easier to remove when the ink is fresh.
Lay the paper flat. Slightly moisten a cotton swab with water and apply it to the ink you'd like to remove, dabbing any excess ink.
Apply transparent tape to the fresh ink and very gently peel it off. Test it on a small area first to determine if this method will be successful, as lifting completely dry toner with tape may damage the paper surface. If it fails, proceed to the next step.
Scrape the offending ink carefully and gently with a razor in one direction. Set the razor at a 45-degree angle as you do this. Use the cotton swab to wipe away any remains of ink.
According to Physorg.com, scientists have been experimenting with different combinations of solvents in order to develop a once-and-for-all cure for removing toner from paper without damage. A mixture of 60-percent dimethylsulphoxide and 40-percent chloroform seems to be gaining approval, with exposure to "ultrasound agitation" to further lift the toner from the paper. This method is still in development and will not be safe to try on your own. Scientists do suggest, however, that this method will be perfected and be used in businesses as a recycling alternative.