Psx bar on bottom question

hello ,

I just started to set up psx trought hyperspin and retroarch . And i have a question . Games like crash bandicoot , when i put native resolution on x2 or higher . I have a bar on the bottom of the screen . On the screenshot its little dark . But it change color . Is there a way to get rid of this bar .

I know on ps2 emu i could change something . Little stretch in height , but on the ps1 emu its not possible with the black bars up and down , en then now that line .