With GNU awk (gawk), using FPAT to define a field as a sequence of non-#@ characters:
$ gawk '{$1=$1} 1' FPAT='[^#@]+' OFS='\n' file >> Sequence.txt
$ 
$ tail Sequence.txt 
HelloMyName
IsAdam
NiceToMeetYou
Similar approach, in perl:
perl -lpe '$_ = join "\n", /[^#@]+/g' file >> Sequence.txt