You can buy hair dye reducers at Boots etc.  They are not that good though - would be better to get the hairdresser to do it.

It depends what you've used.  You might not get it out until it grows out.  My advice would be an early visit to a hairdresser.  

Depends on the type of dye you used.  If permanent they will have to grow out or see a good professional hairdresser.  If it is one of the 6 eeek ones just keep washing your hair and it will soon lighten up.

As queried, was it permanent or temporary? I'm going to say something your mother might say - why on earth would you do something so major with your hair and do it with something fron Poundland????? Or do you mean a well known branded one at a reduced price?

Then I can't think what possessed you....

Treat it as a life lesson.

Different can be startling at first, but there's nowt wrong with brown hair.  Give yourself a chance to appreciate it.

Otherwise, invest in a wig.

It doesn't matter if it was a dye from Poundland or an expensive one. I made the mistake when I was younger of dying my hair and it went jet black.  I used a reducer to get rid of it but I had dark hair anyway so it did it's job. If you are blonde it will be harder to get rid.  You probably need to go to a hairdresser and they will probably need to put peroxide on your hair and then dye it back to your natural shade of blonde.

Head and Shoulders shampoo.  If the blonde was also a dye, you should see a hairdresser.

^ That's not going to take hair dye out of you hair

No, it won't. Get yourself to a hairdresser - and take the packet the dye came in with you.

Shave your head and pretend you had chemotherapy. 

Then surely your hair will grow back in its natural colour 🙄

If you have access to a hose use it to remove the dye by a combination or erosion and dilution.

Have you spoken to a hairdresser, treacle?