easiest way to delete backslash from file name

With the Perl-based file-rename:

$ rename --version
/usr/bin/rename using File::Rename version 1.10

then using a sed-style regular expression s/pattern/replacement/:

$ rename -vn 's/\\//' \\*.txt
rename(\jsandkjasn5.txt, jsandkjasn5.txt)
rename(\jskadn.txt, jskadn.txt)

With util-linux rename (which takes simple pattern replacement arguments):

$ rename.ul --version
rename.ul from util-linux 2.34

then:

$ rename.ul -vn '\' '' \\*.txt
`\jsandkjasn5.txt' -> `jsandkjasn5.txt'
`\jskadn.txt' -> `jskadn.txt'

(you can use \\ in place of '\' if you prefer). Remove the -n (no-op) switch once you are convinced they are doing the right thing.

For completeness, using mmv:

$ mmv -n '\\*' '#1'
\jsandkjasn5.txt -> jsandkjasn5.txt
\jskadn.txt -> jskadn.txt

Or a simple shell loop:

$ for f in \\*.txt; do echo mv "$f" "${f#?}"; done
mv \jsandkjasn5.txt jsandkjasn5.txt
mv \jskadn.txt jskadn.txt

(remove the echo in this case).