Useful commands

Names["Global`*"]
	Lists all variables in use

Clear["Global`*"]
	Clears content of all variables

Clear["A*"]
	Clears all local variables starting with A

Remove[ϕ]
	To get rid of all assignments like (Subscript[ϕ, 1])

See also 2.6.8-2.6.12

?C*
	List all Commands beginning with C

Useful stuff

(Subscript[F, z ]) =  Symbol["x"]

A  =  (Subscript[(SymbolName[F]), SymbolName[z]])

A  =  Remove[F]

U  =  (Subscript[F, z]);
FullForm[U]

U=Subscript[F, "z"];
V  =  (Subscript[F, z]);

z = 5;
U
V