Spreadsheet - Strange Content

[Thomas_Sch]

my fault. the double colon is wrong.
E1:ZZ4:={{}} should to it.
If you want to erase only one row or one column, e.g. E1:E4, or E1:ZZ1, use {}
E1:E4:={}
E1:ZZ1:={}
Don't enter this in a cell, use the "entry line".

Edit.
If you want to erase a single cell, like E1, use the Backspace or [<X ] key, directly below 'CAS'.
Otherwise the contents you mentioned is really strange.
If the mentioned steps don't work, you could reset the spreadsheet by using Shift Esc (labeled 'Clear').