Erase colors un smartsheet


I have several sheets were I have this colors in certain columns at the bottom of the sheet. I tried to change the color to automate or in color white and then I save it, but every time I open the sheet again they are still there, I don't know if it's because I used a default sheet and that's why they will always be there, but it's stressfull because it makes the sheet to look dirty and not presentable. Can someone tell me what's going on? :(

Thank you!